Commons leader Peter Hain has said he was told that "al-Qaeda operatives in Britain were focusing on Parliament" by security services.
This comes as an undercover reporter from the Sun reportedly smuggled a fake bomb into the Commons, where he was working in the catering department.
This happened only a day after five pro-hunting protesters burst in to the chamber and started shouting at MPs.
In May, a Fathers 4 Justice campaigner threw purple flour packages at Prime Minister, Tony Blair, when the Commons was in session.
On Monday, a protester from the same fathers rights group, scaled Buckingham Palace and staged a five-hour demonstration.
Are you concerned about breaches in security? Should access to the Palace of Westminster be restricted further? Does this incident threaten democracy? Do protesters go too far or do they need to be extreme to get their message heard?
This debate is now closed. Read a selection of your comments below.
The following comments reflect the balance of opinion we have received so far:
The security offered to the House of Commons is laughable, to allow one incident to occur can be explained as a mistake, now that we have witnessed the third, serious questions need to be asked of the security measures in place. However, the three incidents in question are prime examples of the frustration of some at the lack of cohesion between the views of the Government and the opinions of the people. The fact that people feel they have to go to these measures to get their point across is something which, I believe, also needs looking into further. Right or wrong in their beliefs, everybody should be able to feel some kind of confidence in their views being expressed properly through conventional Governmental means, and at the moment, that does not seem to be the case.
Steve, Stevenage, England
Why is this so surprising? We have made ourselves a media driven society, worshipping the cult of celebrity, where nothing and no-one is important unless regularly appearing on TV. Peaceful protests are useless, because peace is not news-worthy. Such publicity stunts will increase for as long they attract publicity.
Whilst watching the incident what was interesting was that the security people present all appeared to be middle-aged men in their ceremonial outfits. Surely the problem is that we need properly trained and armed younger, fitter guards present to protect the building and its occupants. Inside both the Palace of Westminster and at Buckingham Palace there appear to be a lot of ceremonial security staff present but no real policemen.
This looks rather like a set-up in order to justify further restrictions of democracy. Today the government is using the Parliament Act to ride roughshod over democracy. What will they use this event as an excuse for?
If the pro-hunt protestors have proved anything, it is that yob culture is alive and well in the middle and upper classes.
Geoff Thomason, Stockport, UK
The commons protestors are only following the example set to them by their government. If you can't get what you want through legal channels - invade!
Good luck to the protesters - it's about time those stuffed dummies who fall asleep on the benches got a wake up call!
Phil, Harefield, UK
I was disgusted by the protestors' behaviour and my immediate reaction was that they threaten democracy. If parliament can't get its business done without being violently threatened then it will be working behind locked doors. This is contrary to our heritage of democracy.
Why are politicians so scared of those who oppose them? The past 24 hours have reminded me of historical protests including the suffragettes. Were they wrong too because they opposed a previous government?
There wasn't a security breach. The protesters had no weapons and no violent intent therefore the MPs security was not breached at any time. It was just a silly stunt and nothing to be worried about
Tim, Bath, England
No, I am not concerned about breaches in security. I think protestors keep democracy alive, and don't doubt the suffragettes were treated with the same scorn as fathers 4 justice are receiving. The current propaganda about terrorism is reminiscent of McCarthyism in the US in the 60's. If anything is threatening democracy, it is New Labours method of government by spin and social control.
Sean, Newport, Shropshire
People seem to think that these high profile security breaches will affect the public's access to the democratic process. What, in fact, these protests show is that the democratic process is an illusion and has been for a long time. You are not listened to therefore direct action is the only viable alternative. It also seems to me that it shows that the 'terror threat' we keep hearing about must be something of an illusion too because there seems to be no effective Security in place to deal with acts on the most obvious of targets. So is the threat 'sexed up' or are our Security capabilities fundamentally incompetent? After Iraq both seems a possibility!
Ben Holland, London
I am more concerned about the likely impact on our rights to see government in action than I am about the actual security breach itself. Here we have a few people behaving like three year olds who cannot have their own way. The pro-hunt people claim that the majority of people are in favour of hunting. The majority of people in the countryside may be but I doubt very much if the majority of town people are and if you ask the right question in an opinion poll you can always get the answer that you want. We have a democracy in this country and whatever you may think about the true representation of the electorate we elected the government and should be grown up enough to accept the good and bad decisions that are made in our name.
How many security reviews are required before our most important institutions have a minimum of protection? How can this happen? Heads should roll.
The UK has the highest number of closed-circuit TV cameras per capita in the world. Despite this, on Monday, and again today, the UK has suffered the humiliation of having two of its state buildings - believed, until now, to be mightily secure - breached by protestors. Doubtless, those intent on international terrorism have made a sinister mental note that the UK's outwardly strong shows of security really mask some serious inner weaknesses.
Bryon Western, Romsey UK
It just goes to show the lengths that people feel they must go to when politicians, who after all quite often forget that they are public servants (including Mr Blair), don't listen to the public who elect them. MPs are no more important than members of the public and shouldn't forget this. We can after all elect new MPs! The demonstration inside the chamber was non-violent as I witnessed on TV and for them to be arrested under these charges makes a mockery of the British police.
Jon, Hampshire, UK
How can we now trust Tony Blair to maintain the security of the country if his cronies are unable to even maintain the security of the House of Commons??
Tony Cross, Bournemouth, Dorset
Personally, I think it is excellent news to see true democracy in action. These self-serving politicians of all hues should get a taste of "real life". A salutary experience for them.
Well, it highlighted how empty the House was... What on earth are our MPs doing? Where are they?
Josie, Wallingford, UK
It's the most interesting thing to happen in the chamber for years! Sad though for democracy in this country. The events yesterday clearly show that an awful lot of people in this country strongly believe that their elected representatives are no longer listening to them - and what's all this going to do to "open parliament"? Make our MP's even more detached than they already are? I wonder which one of them opened the door to let the protestors in?
Chris Briggs, Keswick, Cumbria
I am astounded at the apparent ease these so called demonstrators managed to get round what is meant to be the most secure place in Britain. If we can't defend our politicians properly what kind of protection should the rest of the UK expect ?
Darren A, Brighton, UK
Act's such as the five men bursting into the chamber only happen because people see their democratic rights being trampled on by a government which seems to want be more Stalinist by the day. People will react to bad government, and it will get worse in my opinion.
mike, Hove England
This has nothing to do with security. On this and the purple flour incident they were helped in by an insider. Put the armed guards away and question the pro-hunting MPs.
Robert, Aberystwyth, Wales.
When people think they have lost the protection of the law they will take it into their own hands. Who can blame them?
Patrick Hall, UK
The hunt protesters did well to invade the house - its just a pity they didn't take their hounds and horses in with them and chased those arrogant Labour politicians out into the lobby.
Donald Morrison, Lochgilphead, Scotland.
Batman did not act in a provocative way. Those who entered the Commons did. One would hope that the resulting actions would reflect this.
G Cole, Bodmin, Cornwall
English eccentricity at its best - that is, those fellows rushing around in tights, long-tailed coats and swords by their sides! Bin Laden et al must be rubbing their hands with glee at the thought of such an easy target!
Stephen, Huddersfield UK
Has anyone noticed that the House of Commons chamber is almost devoid of Members, despite the "historic debate" that is taking place. Where are they - in the bars and restaurants as usual, waiting for the division bell to tell them when to vote.
Personally I quite like the fact that unlike in the US or other countries these protesters could get anywhere near the debating chamber without being shot.
I think these protest are born out of a feeling of frustration that the usual methods of protest are not listened to (anti-war marches, countryside marches, superhero protests), and the only way to really make our MPs sit up and listen is this direct approach. They should be grateful that the intruders were harmless and not terrorists.
Clare, Buxton, Derbys
The Commons invasion was just a bunch of idiots exploiting a security loophole. At the time of the incident, the biggest threat to British democracy was absent from the chamber.
Chris Hunter, Bedford, England
Madam deputy speaker was seen on TV calling the Police directly from the speakers chair following the incursion. She was told that an officer would be with her in about 3 hours
This was a disgraceful attack on Parliamentary democracy and the rule of law. Campaigning and winning one's argument at the ballot box is the only option for civilised societies. But how far does media coverage encourage such stunts? The media's preoccupation with sensationalism is deeply irresponsible.
Matthew Ross, Belgium
I have been to the Houses of Parliament a number of times and was impressed how ordinary members of the public could visit their MPs to ask them for help. It would be very sad if the parliament building became a fortress that split MPs from their constituents. This would seriously damage a key part of our democratic process.
I don't agree that the law be broken to put over your point but the protesters that entered the debating chamber shows how easy it is to bypass so called security if they had been suicide bombers it would have been all over for the building and the people inside so I congratulate them for showing disgraceful security lapses and possibly preventing a massacre hopefully lessons will be learnt and put into being.
Ollie, S Wales
The amount of fuss being made about a simple and quite harmless intrusion has to make you wonder if there is a hidden agenda here. Do our politicians still think they have the right to remain so far away from the public? Don't they realise it is this refusal to listen that leads to these actions and violence? (They do - do they care is more apt a question. The police take the rap). Is there a chance this harmless show will lead to even more distance ( i.e. armed police and barriers ) between politicians and the public? I think yes.
Jon Hansen, Basildon, England
The behaviour of the protesters, in disrupting, inside and outside, the democratic workings of Parliament, show how disingenuous spokespeople for the pro-hunting lobby are when they claim to be law abiding. Fox hunting is a violent activity, and its brutality is, on the evidence of yesterday's behaviour, mirrored by the thuggery of its supporters.
Ian Reader, Lancaster, England
There is only one question to ask here: Who benefited from this latest security breach? Certainly not the pro-hunt movement. But with new police powers to restrict demonstrations and ban permanent demonstrations in Parliament Square, and the Civil Contingencies Bill being discussed in the House of Lords the very same time the Westminster breach happened, only those longing for more clampdowns on public opposition will benefit from this.
Jason Parkinson, London
It's absolutely unacceptable this kind of security breach which took place in the House of Commons. It shows the vulnerability of our so-called tightened security. According to the difficult circumstances we're in every security issues must be scrutinized and I hope we learn our lesson so this won't happen again.
Jama W. Hassan, Southall, England
In recent intrusions, "security" has not even fired a warning shot. Clearly, every officer in this country is afraid of being sued / disciplined / fired if they dare to do their job properly. I don't blame them, they've been put in a lose-lose situation.
Ray Gray, London, England
What is all the fuss about? The protestors weren't armed and could not have been due to entrance security procedures, so there was no potent danger to anyone. It is ridiculous that when an event like this occurs the word 'terrorism' is banded around like a hot potato. It is also ridiculous that blame is being left at the shoes of the protestors. Their actions merely show the plight of their cause and the emotion it stirs. They were given an inch - of course they're going to the M25. It's time politicians started taking responsibility for their decisions and refrain from inciting hysteria as a result of events like these.
Matt , North London
The United Kingdom is a civilized and democratic country. Our Parliamentarians are elected by their constituencies to speak for them in Parliament. Whilst peaceful demonstrations have a relevant place in the political dialogue of the country, mass violent demonstrations are a direct attack on our way of life. I would be very interested to know how many of the protestors yesterday are members of the party that campaigns on the hypocritical 'Law & Order' platform. Do they have the stupidity and arrogance to think that they were showing us the iron fist in the velvet glove? I very much look forward to seeing police in riot gear charging them again and other concerned citizens showing them what 'direct action' really can mean on a personal basis.
James Millar Fisher, Edinburgh Scotland
Isn't it a positive reflection on British Society that both "security breaches" were dealt with relatively peacefully? If the same had happened in many other nations, there would likely have been shots fired and injury sustained.
Leona McPherson, Glasgow, UK
I think we're going to see more of this kind of thing - people taking direct action. Speed cameras, red tape and petty rules are making more of us into criminals, whilst the police and parliament do nothing effective to protect us from the serious threats. MPs are not respected, because people don't feel they do anything to deserve respect.
Adrian, Reading, UK
The hunt protesters did well to invade the house - it's just a pity they didn't take their hounds and horses in with them and chased those arrogant Labour politicians out into the lobby.
Donald Morrison, Lochgilphead, Scotland.
I see that the invaders have been charged with "Violent" behaviour. Running into a room and pointing a finger is hardly violent. Hitting women with truncheons is violent. One rule for one and one rule for another
Kevin Miller, Warrington, Cheshire
Sadly we have come to a point where the traditional "peaceful" protest is ignored by all. This means people have to resort to something out of the ordinary just to get the government and media to take notice, would anyone have even heard of Fathers For Justice if all they did was hang around waving placards? Respect to you Batman and good luck with your cause.
Rob Hughes, Rotherham, UK
I see that armed police will now be guarding the Chamber. Is this to keep protesters out, or to keep the increasingly remote and out of touch politicians in?
Alan, Rochdale, England
We are being constantly told by Tony Blair that the Nation is on permanent alert from terrorists. So why are these people getting into Buck house and Parliament so easy. Is this another load of spin (lies) from this hopeless government.
Tony Westgate, Horbury, UK
Combined with Windsor castle and Buckingham Batman this shows just how second rate Britain's security services are despite spending billions on them. Now that the powerful see how badly they are protected they might finally listen to the rest of us (taxpayers with votes) when we complain about unpoliced Britain.
Jim, London, UK
As usual, Britain is shown as a comic, totally inefficient nation. Current security is obviously a joke which is odd considering the scores of security "experts" we have in this country who are appearing constantly on 24 hour news programs!. What do they do all day? The latest breach during the hunting debate looked like a Monty Python sketch......public schoolboys being wrestled to the ground by men in tights!. It beggars belief!
Jamie Easton, London, England
If our politicians actually bothered to stop and listen then people wouldn't resort to such extreme ways of getting a message across.
I'm more worried that there was only one armed guard and he was armed with a sword. If he had a truncheon he'd probably have used it to subdue the protesters, and I think having a marksman or two is just common sense, I don't want to see any protesters dead but if one was shot in the leg I'm sure the rest would stop and give up.
Jon, Melksham UK
As the title of this topic illustrates we are all talking about security, and not hunting with dogs, or father's rights. Dramatic as this week's protests have been; they have not succeeded in focusing debate on the causes the protestors wish to promote. Hardly an effective strategy.
John F, Macclesfield, UK
I'm so depressed that in a world that seems to be descending into anarchy, people no longer feel a duty to act responsibly and support the democratic process. Does anyone really want to live in a world where people try to get what they want through intimidation?
Chris, Southampton, England
I think it laughable that many commentators are talking about this as an affront to Parliamentary Democracy. We bid a fond farewell to that when (a) the Government decided to ban hunting against the evidence and (b) when it was disclosed that the Parliament Act would be invoked to clear this Bill through the Lords. Frankly, I am far more worried about my family's safety following our involvement in Iraq than that of these petty destroyers.
Like others, I am proud to live in a country where protests are legal. I joined the giant protest against the Iraq war. However, it was chilling to hear on the news coverage two protestors threatening a civil war. This protest seems to be the start of an anti-democratic campaign.
Peter Head, Edinburgh, UK
Our elected representatives seem to have lost the plot. The House of Commons was established as the peoples' house to enact legislation in line with the wishes of the people. The Commons hunting votes have not remotely approximated the results of any survey I have seen. In any case, while most people will have a view on the subject I suspect that other than the mostly loony animal rights people, the huntsmen and women, hunt supporters and those whose livelihoods are threatened, most people have no strong views. It is absurd to threaten to ram through this Bill by using the Parliament Act - itself possibly subject to legal challenge.
David, London, UK
I don't know why people are complaining so much about the protestors. In fact they are doing the security services a favour by highlighting lapses in security. So fair play to them I say!
I have no particular love for most politicians but it is essential that the chain of command of government (including the Royal Family) is maintained. Intruders in the Queen's bedroom, comedy terrorists crashing birthday parties, Batman at the Palace, flour bombs at the PM and now this... Yes it's very funny - in fact, it's making us a laughing stock internationally. MPs (and others) worry that by protecting themselves they will trample our civil liberties. I think my civil liberties will suffer more when old men in tights with swords don't stop a suicide bomber from paying the front benches a visit.
David, London, UK
The flour "bomb", the palace invasion, (by Batman, no less), the "storming" of the commons - personally, I think it's inspiring that members of the masses can still use elaborate protests methods, and get the police and media all wound up!
All these stupid people achieve is to weaken our already tenuous hold on democracy. Soon, thanks to people like the hunt protesters and Fathers for Justice, we'll have no access to parliament and the political process. Why won't the protesters realise that all they do is turn people away from their beliefs by their immature and irresponsible actions?
What I want to know is why John Prescott didn't hit them?
This incident only raises more questions of how safe we all are?
Zak Kahn, Glasgow, Scotland
These protests have crossed the line of acceptability. These people just don't know how to behave in society and therefore should be removed. It is only by keeping within the boundaries of acceptable behaviour that we can function as a nation and all get along. Beef up security to ridiculous levels and send the bill to these idiots.
Tim Holloway, Dereham, England
Has nobody noticed that in the last 5 days security has been breached 3 times! If they're so worried about terrorism rather than send out leaflets to all the homes in the UK about what to do during a terrorist act, why not deal with the fact that regular people can get into a high security place?
Suzy Lynam, Sevenoaks, Kent
It certainly makes the terrorists look stupid - they spend months and months carefully planning methods to attack the core of government when all they have to do is to get a bit rowdy and run through the door.
Keith, King's Lynn, UK
I fail to see why politicians have any right to expect to be any safer than the rest of us.
Barrie, Harlow, UK
I watched the "deeply concerned" reporters and "anxious" MPs on TV, as I did on Monday. I couldn't share their concern. Frankly I was laughing. I'll soon switch off as David Blunkett will manage not to blame anyone, announce another security titbit for the media, blame the hunt protestors for an attack on the mother of all democracies. That's the boring side to it all. Even living in London, Parliament seems too remote from the people. I used to be someone who believed in the vote and peaceful protests, but I can sympathise with those who feel that this government is now too far away from the people it tries to govern.
Jennifer, London, England
No I don't think access should be further restricted, after all it was these people who voted for war and they should have the courage to face the consequences of their actions. As for extreme campaigners, if MPs listened there wouldn't be a need for them! These protests will increase once MPs have created a nice safe haven for themselves and distance themselves further from the public.
Chris, Holyhead, Anglesey
I for one am pleased that we live in a country where this sort of protest can happen. Whilst I cannot condone the scenes outside the Palace of Westminster today, I feel that the protest inside and that on Monday at Buckingham Palace are uniquely British. It is something I am proud of. Who would want to be like the USA where anyone who tried to pull of this kind of stunt would be shot before any questions are asked? It is all well and good to elect an MP by democratic means, but if during the course of five years that MP is not representing your point of view, it is only right that you make you own point known.
It's right that politicians are subjected to these extreme methods since they are contemptuous of the will of the people. They should not be voting in parliament in accordance with their conscience. Each MP should be voting in parliament in accordance with the instructions of their respective electorates.
Brian Langfield, Yorkshire - UK