At least 270 people have been killed following explosions in the Iraqi cities of Karbala and Baghdad.
The blasts took place as Shia Muslims marked the festival of Ahsura.
It was the first time in decades that the majority Shia community had been able to observe the holy day and security had been tightened as a result.
US and Iraqi leaders blamed the carnage on a man accused of links to Osama Bin Laden's al-Qaeda network.
But the top Shia cleric, Ayatollah Ali al-Sistani, criticised the US for failing to secure the country's borders from foreign attackers.
What can be done to restore stability to Iraq? Send us your comments.
We will be discussing the situation in Iraq in our global phone-in programme on Sunday 7th March at 1400 GMT on BBC World Service Radio and Online. If you would like to take part in the debate please include a telephone number where we may contact you. This will not appear on the site.
This debate is now closed. Read your comments below.
The following comments reflect the balance of opinion we have received so far:
Can't believe I'm saying this, but I think Iraqis were better off with Saddam. No one can save this situation, no one.
PM, NY, US
Unfortunately attacks like these will happen often in Iraq until its neighbours stop the terrorists' support.
Willy Khoury, Beirut, Lebanon
It makes no difference who is responsible for the attacks. The war in Iraq has not made the world or even Iraq itself a safer place. The resulting chaos leading to the instability we are seeing was predicted by most of the world's governments, particularly those in the Middle East. 150,000 highly trained coalition troops can't keep the peace. How will the 40,000 strong rookie Iraqi army that the US has agreed to cope?
Nigel, Oxford, UK
Whether or not Iraqis want the Americans and British there seems beside the point. The war to topple Saddam Hussein was, unfortunately, just that. It is all too obvious that none of those who claimed the war was necessary really took the trouble to plan ahead. This is in stark contrast to the Allies in WWII, for example (although their planning did not always work out either). Iraq is going to remain a problem - much as Afghanistan will - and no amount of good will alone can fix what has been broken.
D Fear, Heidelberg, Germany
Didn't the US governing authority anticipate this? Why did they take no measures to prevent this from happening? Do they really care about Iraqis or are they just trying to bleed the country dry of oil.
The situation in Iraq is a violent one now and will be for some time to come, however, I for one would rather live under an uncertain democracy than a certain dictatorship.
Sam, Washington DC, US
If these attacks are a result of the US/UK invading Iraq, why were 20 Shia's also killed in Pakistan today? This is sectarian murder by Sunni's on Shia's. The Sunni community needs to come out strongly and condemn these attacks, and then find the perpetrators from within their own community.
Despite the blasts, isn't it a good thing that this festival was allowed to go ahead in the first place? Surely that's what's come out of the war: freedom. For all the doomsayers - yes, this might not have happened if the war hadn't gone ahead, but only because the Shia people would have been too scared to even try. A sad day.
There is hope for peace but it may be sometime in the future. Certainly the divisions in Iraq need to be repaired. If only the Sunni and Shia would take to heart the teachings of peace that is central to Islam - but who among the clergy has the courage to stand up and preach this with patience?
It takes time. Rome was not built in a day. America took a long time to heal itself after we established our democracy. Time.
David, Philadelphia, USA
Only Iraqis can bring peace to their country. It's time for them to step forward and seize the day. The Iraqis have a historic opportunity to forge the direction of their country and its high time they do it.
Michael Mackay, Falls Church, Virginia, USA
I would like to ask those who condemn the actions in Iraq and oppose America's role just one question. Given the chance, would you turn back the clock and return Iraq to the days of Saddam and his regime? I ask that because it is fact that without the US and UK intervention in Iraq, Saddam's regime would still be in place today. So you all think that is preferable?
Mark H, UK
A lot of people are trying to argue that the question whether this war and the occupation are justified or legal is of no importance and we should be looking to the future. In my opinion those questions are essential because we should be looking towards the future. If this war was legal/justified does it mean that we are going to conduct more of these types of wars? Let as hope that this war teaches us the lesson that unilateral measures create more problems than they solve because the future of the whole planet may depend on Iraq and not just the future of the Iraqis.
Mitsara, Athens, Greece
I'm really amazed that people believe Iraq was better under Saddam, or that Saddam was a great peace loving leader, who cherished all he's people. The World for the citizen of Iraq has change and is still changing for the better, the trouble is that a small minorities of Arabs have a misplaced loyalty against all 'Western Governments' and especially the United States.
The UN have said that Iraq wouldn't be ready to hold elections until later 2004 or early 2005, this has little to do with the actions of 'liberating collation forces' but the neglect and tyrannical treatment by Saddam and he's followers towards the people of Iraq.
People still complain about the actions of 'Washington and London' in freeing another whole nation of people. It was morally right to free the Iraq people from a tyrant and to aid in rebuilding their country, and to one day give support to open and free elections.
Steve G, Gateshead UK
There will be a time for peace in Iraq. That time will be when the US is seen as impartial and the rebuilding of Iraq is being done by Iraqis. A UN force would have been a viable method to rebuild the country, but it is the US and Britain that bears the responsibility for their non-cooperation through ignoring their decision and greedily handing out contracts to large US companies. In my view, the effect of the US, Britain led war has created the largest terrorist training ground in the world.
Will Bugler, Hereford, England
An admittance that the war was illegal, wrong, naked aggression, based on nothing but lies and supported by a smug western media and a disaster on the world would be a nice first step. Now we can only patch up Iraq. Ignorance and fear have destroyed a country. That admittance is the first step.
Michael Harris, Ireland
Leaving the Iraqi people in a state of vulnerability would defeat the hard work of service men and women who have sacrificed and risked their lives to "dethrone" Saddam. Controversy over whether the US should have even been there is over. It can't be undone. However, since the US undertook to "help" the people of Iraq, it cannot just decide to pick up and leave simply because the country's dictator has been captured. The US needs to help the country be able to prevent someone like Saddam from reigning again, thus putting the US and Iraq back to square one.
Steph, Idaho, USA
The US attempt to liberate Iraq from Saddam has given the Iraqi people nothing but death & fear.
Ashoka Nissanka, Colombo, Sri Lanka
To Ashoka in Sri Lanka: You wrote--- The US attempt to liberate Iraq from Saddam has given the Iraqi people nothing but death & fear---Please explain how that was any different when Saddam was in power. The Iraqi people at least have a chance now to build their own nation. Easy to throw stones, Sir, but rather hard to do something beyond the words.
Lisa, Wisconsin, USA
What is wrong with US? Anything which goes wrong in the world for which they don't have an answer they resolve it by blaming "Al-Qaeda". Mr Bush please get more proof which you can show us then blame. "Innocent until proven guilty" Remember
Something here is funny, terrorists exploded the bombs and killed the people but some are trying to blame Americans. Let's pretend that Americans are their enemies, why are terrorists killing innocent Muslim civilians? Again, had Americans attacked Bali or Turkey? It seems to be a war between bads and worses!
How does one restore order? By fighting against the perpetrators of these terrible acts. And who is responsible for these bombings? Al-Qaeda, of course! And how do we know its Al-Qaeda FOR SURE? Because we have been told so by the US intelligence services, the same folks who stubbornly stuck to their claims of the existence of WMDs, and who now have been wholly discredited. So where does that take us? Back to square one.
We should have finished the war in 91, as the population were motivated to upraise then, 10 years of UN sanctions has turned them against us. I don't think that we can make peace in Iraq, they hate us now, it's typical of US foreign policy to drop the ball when it is critical to carry on.
Travis Dryden, Melbourne, Australia
Wasn't it the US who said "without Saddam the world will be a better place"? Well obviously not! Its just as bad!
Ahsan T, London, UK
What can be done? It is being done! The free Iraqi's are plotting their own course to self determination & democracy. The people who criticise America & the UK should remember one thing - America & the UK have put their money & their youth where their mouth is - whilst the rest of the world hollowly cries decency. To save all this I guess we should have cut a deal with Saddam. Then the liberal left would have another mode of attack - accusing us of propping up & supporting a bloody dictator.
Roger Morgan Freedlan, Whitwick, England
It is important to note that Asyura is not a religious celebration. It is political in nature. It is also historical as it marks the disappointment of some that Muhammad's grandson was not given the ruling post of the Islamic empire. It is one thing vying for a living politician but absurd when supporting a dead politician. The Occupiers have chosen to support the Shias and their nonsense under the guise of religious freedom when this matter is purely political. Hence the use of "divide and rule" tactics again by the 21st century colonial powers.
Arbibi Ashoy, KL, Malaysia
While the USA won the war with much ease, winning the peace is likely to remain elusive. Seems like someone forgot to do their homework...
Asma Chaudhry, Oslo, Norway
By starting this war without having a clue what to do when the actual fighting was over the coalition opened Pandora's box.
Now the coalition has only option left: stay there until the country is stabilised or (preferable) until a UN backed replacement force arrives which has a strong mandate and which has troops from various parts of the world including the Middle-East but excluding Iraq's neighbours.
Filip, Antwerp, Belgium
US and UK must leave ASAP. There presence is not welcome as we can see. They must provide finance for the destruction they have caused through a third party who would be welcome, for example UN. How arrogant US were to announce that only US companies will get contracts to rebuild what US military destroyed! Well I suppose that this is western "democratic forces" and "market economy" is all about.
When USA murders innocent Iraqis it's "liberation". When anyone else does it it's "terrorism". America showed that violence and ruthless killing can be used to achieve strategic goals. The terrorists are just copying their "success".
In the last few months, all the victims of the terrorists' attacks in Iraq have been Iraqi police and civilians, with hardly any American or British soldiers being killed. Therefore, the occupying forces of the CPA should apply the same methods, which appear to be working, to protect the ordinary Iraqi citizens and police force, as being used to protect their own people serving in Iraq.
Zaid Al-Hindawi, Iraqi in London, UK
Terrorists attacks are frequent, but what is less mentioned is the good that we are doing in Iraq. Once public services are built and a government is constructed, the US will be closer to leaving and Iraq can start anew. But the US still has a lot of work to do to stabilize the country and crush the terrorist resistance.
Tim, Bethesda, MD, USA
We were made many promises by Pres. Bush as we headed into this war, but I believe, none of them have been kept. We were to be welcomed as liberators and we are targeted as occupiers. We needed to address the most pressing threat to our country when in fact Iraq posed not threat to anyone. The threat was hiding in Pakistan where we were unwilling to look for it. We were to make the world safer and have only managed to create even more enemies who threaten us every day.
Peter Friedrichsen, Shelburne, VT USA
It seems in the eyes of the rest of the world America is the root cause of all that is wrong no matter what course of action we take. This situation is a perfect example. If we did have tighter security at the festival, we would have been criticized for being overbearing, controlling and how we need to leave Iraq as soon as possible. Instead, we stepped back and let the Iraqis handle their own security and have been roundly criticised as well.
I cannot believe that the United States has allowed the horrendous security situation in Iraq to go on. It seems to me that even with Saddam gone, the situation is deteriorating at an even faster pace. Sometimes it seems as if the country is perhaps already seeing the beginnings of a major civil war. Clearly the Bush administration has a lot to account for, it does not seem like an exit strategy is defined or even existent.
Aram, New York City, USA
I am young Shia Muslim living in America. I often pray at Sunni mosque and try to bridge unity. Recent events I believe show that the biggest enemy to Islam are the Wahabbis. Islam is a faith of peace, never calls for offensive attack on innocents - regardless of faith. I have never heard of a Shia opening fire in a mosque, bombing someone, or discriminating against their brothers/Sisters of faith. The world needs to act as these people must be stopped.
Shabir Ali Khan, Piscataway NJ USA
Just a few days ago here on this website people were talking about God and religion. Most agreed that God means love, peace and humanity. I wonder what has happened. I can not imagine some people killing others, more so in such religious festivals, if indeed the culprits believe in God. The culprits should be brought to face justice. Blaming America is not the solution; after all it brought the Shia this freedom. The killers are terrorists including those who killed Shia in Quetta, Pakistan today.
Kajobinyi, Alexandria, Egypt
Americans must know Iraq belongs to Iraqis and they should themselves determine the fate of Iraq .And also Iraqis should settle their religious differences and reconstruct their homeland together and show that they deserve to govern their country. I hope the UN help these people who were under oppression for 30 years to held a fair election.
Azadeh A T, Tehran, Iran
We knew before the war that the Iraqi opposition were at each other's throats. We knew before that Western values are despised by many in the Middle East. Surely this dreadful quagmire in Iraq was entirely predictable?
Geoff Payne, London, England
One always wants to say what should be done. But after the invasion of Iraq and the removal of all government the situation is clearly hopeless.
As a Shia, I can tell you that today is the one of the holiest days for a Shia Muslim. Emotions run extremely high, this attack has been very carefully planned to directly tap into those emotions and people are hoping for retaliation. Whoever did this, I can say with near certainty, wants Shias to fight Sunnis.
You can not force the democratic ideals onto people. American ignorance and hidden agendas for this war has created a situation where there will be many more deaths. Peace in Iraq will be up to the Iraqi people once the obnoxious occupiers leave.
Whatever your opinion on American intervention in Iraq, it would be wrong to pull out now. This is obviously a concerted attempt by terrorists to start a civil war and destroy any hopes of a democratic Iraq. The laughable thing is that this terrorism is also being orchestrated by outsiders so the only question is who really has the best interests of the Iraqi's at heart?
To all those people who blame the war for this: OK, let's have Saddam back. He'll sort this all out, that is what you're saying after all!
Mark G, Oxford
In my view America should leave Iraq to Iraqis, so as to have a peace and tranquillity in the region.
Bush said the aim of this was is to make the world safer, well surly it didn't make it safe for us Iraqis.
Dia, Baghdad, Iraq
I feel sorry for the innocent people of Iraq, but I am also concerned for the wellbeing of all the British troops in Iraq, put there by our incompetent leaders. Did anyone, ever believe this would not happen...?
The people who did this will not gain anything from it; they are a relic from the past. Saddam will never return. The US is in a very difficult spot, you have a society that is very tribal, it's very hard to please everyone. No matter what happens one segment of the Iraq society will feel left out. The US is there to help. Who was going get rid of that mass murder? Remember freedom is not cheap. The US has paid in blood what other countries give lip service to..
In recent years we have seen the beginnings of an Islamic Reformation. Shia vs Sunni, Moderate vs Fundamentalist, these battles will shape the future of our planet. Our Reformation was fought out in Europe, this one will be global.
The US promised the security of the Iraqi peoples but now they are worrying about their own. Cleary they got it wrong at the first place and it is not the first time!!!
The murder of members of opposing ethnic and religious groups went on under Saddam Hussein, and on a much bigger scale than we have seen since he was removed. The difference is that then it was done in relative secrecy, in a country where foreign journalists were not welcome, and thus didn't make the news. Do these attacks mean that it was wrong to go to war? No - they mean that it is time the Iraq people learnt to live with one another.
Andy B, London, UK
We can all very easily place America with blame, and in hindsight come up with brilliant solutions but the truth is this was never meant to be simple. A coalition presence needs to remain in Iraq and just see this problem through┐ no easy quick fix.
Bill Tsoukalas, Sydney, Australia
I am sick of the moralising, sanctimonious people who say 'those of us who protested against the war saw this happening'. If we had not freed these people from this tyrant, the majority Shia people would still be under the cosh and not even be able to celebrate their religion in the first place.
The only thing that will bring peace and harmony in Iraq is if an Islamic state is established. The British and the US need to get out fast and leave the Muslims to deal with the dilemma.
The UK and US should leave Iraq immediately and stop meddling in our affairs. Iraq's problems stretching back all the way to the 1920's are a direct result of US/UK interference. We did not want Saddam, when the UK and US did and now we do not want this occupation when the UK and US do. Get out and stay out, it's as simple as that.
The hope for peace vanished when the coalition started this pathetic war. Now Iraq is an open wound and it's going to take a long time to heal it. I am not even sure the UN will do better that the US/UK to bring stability. The answer is within the people's hands.
Xavier R, France
I am Kurdish currently living in London. I would like the coalition forces to stay in Iraq as long as terrorism exists and I think the US and UK have done a very good job.
Allan Foad, London
Many who supported the need for war also saw this coming. That is not a reason for inaction. Measure these atrocities against those that occurred throughout Saddam's reign.
The only practical thing that can bring peace to Iraq is to redraw the borders of the country. "Iraq" used to be 3 provinces of the Ottoman empire - a Sunni province, a Shi'ite province and a Kurdish province (plus what would become Kuwait which was always semi-autonomous). I'm not convinced it's totally desirable, but it's probably the best solution to the problem. Kuwait has certainly prospered from its independence.
It will be very difficult to stop attacks like these. There are a number of terrorist networks, and they are beginning to converge on Iraq, because that is where the action is. The US needs to do a better job of infiltrating terror cells, so that they can have a chance of preventing atrocities like this.
David, Milwaukee, WI, USA
If all that held Iraq together was a British Empire map maker and a brutal dictator perhaps it is better that it goes federal or breaks up peacefully than be forced to stay locked together in mutual fear and violence for the stability and profit of other nations.
James Scobbie, Scotland
It seems amazing to me that we did not see these problems happening before we went into Iraq. In a country that was obviously divided by race and religion, what did the powers that be expect to happen? Everyone forgets their differences and get along just fine? I don't think so.
Once again, America's peace initiative is falling like a pack of cards with scores of people dying almost every hour in Iraq. Message, democracy cannot be bought nor forced on people, every society should be allowed to evolve based on its historical, religious and cultural antecedents.
Joel Ik, Ojiakor, Lagos, Nigeria
Saddam stabilised Iraq with a secular government that ruled, albeit oppressively, all religious factions more or less equally. Power will now go to whichever religious majority can seize power while others will try to dislodge it. There is the recipe for carnage for years to come.
Mark Bretherton, Alberta, Canada
There is never going to peace in Iraq. It's obvious that the different religious factions are going to wage war against each other now and for ever more. Because although the UK and the US are hated there, all Arabs hate each other just as much. Iraq will have to be split into about 4 separate countries in order to maintain any semblance of peace, and even then they will argue over borders. You will need someone as powerful as Saddam to maintain order, and you've just got rid of him.
People call for self-rule in Iraq as if that would solve all its problems, but these explosions are nothing to do with the coalition forces and everything to do with opposing Iraqi religious factions vying for power - exactly what would happen, but more so, if the coalition pulls out. It is an unfortunate fact that when religion and power are closely linked there is very little room for discussion and compromise. There are no easy answers.
What hope for peace? None whatsoever, I'm afraid. What's happening in Iraq now is a direct result of American intervention. If they hadn't invaded, this wouldn't be happening.
Anonymous, Liverpool, UK
We are now starting to see the worst consequences of the war in Iraq. The argument that undermining international law and killing thousands of people to remove one man from power was worth it is starting to wear thin. Iraq faces a very uncertain future and possibly one much worse than it would have had under Saddam Hussain. I wish that Tony Blair and George Bush had listened to the world and maybe we could have found a better way of removing Saddam that didn't lead to such massive suffering.
We saw it coming. Besides, this is mainly al-Qaeda and Saddam loyalists who are perpetrating these attacks on the innocent Iraqi people. They are trying to start a civil war between the Sunnis and the Shia. I hate to break it to most of you, but most Iraqis WANT America there.
Paul, USA: America is full of arrogance. We don't want you there. We wanted a neutral force to supervise and solve Iraq's problem. The US has simply messed things up and could be the cause of outright civil war very soon. Get a grip America and solve the mess you caused.
Tahir, An Iraqi Citizen,, London, UK
To Paul, USA. As an Iraqi, I hate to break it to you but most Iraqis did not want American troops in the country. And if your hawkish Bush administration had done their research prior to colonising my homeland, they would have come to the conclusion that even before Saddam there were tensions between Sunnis and Shias.
This is only the beginning... a post-war country is usually worse than a war country. A civil war has been boiling... by June when the Americans hand in power, things will get worse thanks to them.
Such attacks against innocent civilians are cowardly and barbaric. We can only hope that the various Iraqi ethnic communities unite against what is a common threat and evil.
Dave Evans, Cardiff
Iraq is a Western colonial concept imposed on a region where different boundaries are more natural. Stability must come from a more federal organisation for the area...but this will not happen in a period of invasion-induced instability.
Let the Iraqis have direct elections that give the elected government real credibility. This is unpalatable to the USA as it will lose regional influence but appears the only way to secure a peaceful Iraq.
Mark Hamill-Stewart, Bangkok, Thailand
The stability of Iraq depends on the Iraqis themselves, the presences of the Americas should not be viewed as an invasion but looked as protection of lives and properties and the freedom from oppression. My advice to the people of Iraq is that they should stop killing each other, turn over a new page and start thinking of building Iraq and making life worth living in the country. My second advice is to America, we know you want peace and stability in Iraq, but allow the United Nations in the driving seat to lasting peace.
Imposing a solution without understanding the problem offers little hope for peace. Iraq cannot have a solution imposed from outside: it must be given time to find its own way forward either as a federal state of three parts (North, Central, South - Kurds, Sunni, Shia) or as three independent states. Help from the West will only be seen as interference as long as the Israeli-Palestinian problem is not given the same kind of help.
John M, Lyne Meads, UK
Until all the coalition forces leave Iraq to the capable hands of the Iraqis and not interfere in their lives they will never get peace. Leave them alone! They are made to feel incapable and therefore the problem is only made worse!
David Hilton, Hudds, UK
What Iraq needs most is a popular, strong president with absolute power.
Bring the UN in. Send the US and UK home. Give the Iraqi people self-rule. Many of those who protested against the war saw this coming. I can't believe the government didn't. It was clearly likely to happen. I'm just sad that we were right.
Christian, Liverpool, UK
I don't agree with Christian from Liverpool. This is a graphic and bloody example of why we went to war. The Shia people were not allowed to express themselves under Saddam and it would seem that some remnants of his supporters will still not allow the Shias any rights. The taking on and defeat of such people is justified. It is now time to stop whinging about the war and to support all the Iraqi people in making sure that their new constitution can be provided and that Iraq has the security and investment that it needs.
Paul Goddard, Newbury