Police are maintaining a high-profile security operation in connection with the London terror attacks.
The chief constable of the British Transport Police, Ian Johnston, says his officers will not shy away from stopping and searching those groups most likely to present the greatest threat.
Meanwhile two men have been arrested in connection with the 21 July failed London bomb attacks following three raids on separate addresses in south London.
Six men and a woman remain in custody after being arrested during police raids in Brighton on Sunday. In Italy, Osman Hussain, who is being linked to the Shepherd's Bush attack, is fighting extradition.
Do you think stop and search can be an effective measure? What extra passport checks should be put in place?
This debate is now closed. Read a selection of your comments below.
The following comments reflect the balance of opinion received so far:
It would appear that anyone, desirable or not is able to enter and leave the UK unchecked and without hindrance. The Home Secretary is on holiday and the government seem to be paralysed and incompetent with regard to decision making on border control and security. This is an absolute scandal - Parliament should be recalled immediately. Whoever is responsible for this mess should be sacked - lives are risk.
I regularly fly within Europe as part of my job. Last week I managed to fly from Dublin and then through Gatwick with no check on my passport or any other ID. The only thing they looked at was the boarding pass - not a lot of point as I could have been anybody. The authorities really do not have a clue
Richard Smith, Rochester England
Stop and search is a good policy, makes everybody feel safe. However the policy of targetting people on their ethnicity will not serve the purpose. It is a reactive policy based on the ethnic background of the 07 July bombers and 21 July suspects. The fact is anybody with a similar mindset to the bombers or suspects can be the next terrorist and it goes beyond the confines of a particular race, religion or sex. I would feel much safer if police search everybody with a bag that looks large enough to hold a bomb. I also feel Stop and Search only is a confidence booster, but cannot stop an eventuality, as the bomber would set it off if the officer stops him/her. A crack down on terrorist cells by police and other intelligence agencies is the only long term solution to make our world a safer place.
Ramesh Bala, London
I am glad to see extra police on the streets, it makes people feel safer (for a change). But my question is why does it take recent events to get police from behind their desks onto our streets?
Adam Wright, Surrey
Why not make everyone entering or leaving the UK hand in a photocopy of their passport photo and information page. Machines could be installed at arrivals for this purpose. There would then be a record of all who entered or left the country.
Trevor Plumb, Colchester, Essex
I think with the horror of our current situation something has to be done. Stop and search on random bag carrying people has to be a positive thing. But it shouldn't be subjective to one ethnic group. Anyone can be a terrorist, and that's the sad and scary fact.
I am a young, male British Asian. The calm restraint of Londoners in response to the July 7th attacks left me with an enormous sense of pride in being British. This was seriously challenged last week, as I encountered repeated looks of suspicion from fellow-travellers on London's public transport. Amazingly, the seat next to me is often left conspicuously empty. On Thursday I was stopped and searched twice on one journey into work. I learnt later in the day that my white colleagues had not encountered any such experience. Earlier in the year I was on holiday in India, a country that has had a long history of terrorist attack. It is not assumed in India that the colour of my skin makes me more likely to be a terrorist. The war on terror is making racist assumptions acceptable in Britain. This cannot be good.
Ashish Ghadiali, London, UK
As anyone who has been unjustly stopped and searched by aggressive police officers will tell you, it is a very humiliating, embarrassing and belittling experience. Yes, desperate times call for desperate measures, and they have my full backing for now, but I hope this will not become standard policy, as the co-operation and good will of the public is paramount. If this power is abused or over used in any way, I fear eventually public support may turn against the police.
Alan Wood, Brighton
Mr Hoon says that identity cards will show who is in the UK at any given time. He is ignoring the fact that Osman Hussein escaped because no-one was checking documents before passengers boarded the train. If nobody checks, then we will be no better off having spent money that could be better given to famine victims. I wish ministers lived in the real world.
Malcolm Blackburn, Chapel-en-le-Frith, Derbyshire
I travel regularly out of LHR and since the terror attacks have been asked for my passport before security screening. The government should either re-impose border controls and thus provide resources for proper screening on embarkation or stop wasting travellers' time with useless passport reviews. The person checking mine on each occasion was not the person checking the boarding card and never once was the passport checked against any data base. From my experience it is clear the procedure at LHR is designed only to look good. It is very disconcerting to think that the government agencies have so little idea of what or who they are looking for that they will waste time stopping me but allow the real suspect escape to Italy!
After the Herculean efforts of the police and security services to track down the bombing suspects, why is it that we are having to ask our 'close EU partner' Italy nicely if they wouldn't mind sending one back for questioning? Any arguments that the man will not get a fair trial should be thrown out immediately by a fellow signatory to the EU constitution.
Lorraine, St Albans, UK
As an Irish ex-pat I recall being stopped on many occasions in the 70s and 80s. It was normal and I did not resent it at all. I did speak with a Northern Irish accent then, and would have considered it inefficient security if I had not been stopped! The bombers are after us all, irrespective of the skin colour; I am sure that as long as the police behave in a courteous manner there will be no problems stopping those with browner skin than I.
M Savage, Manchester, England
As an Asian, I personally don't have a problem with being stopped and searched or any other measure. What I do find an issue is the conduct of the police and the like when they carry out these measures. Treat me as innocent UNTIL proven guilty. There is no need for that dirty stare or the accusative tone. Like all criminals these criminals will attempt to employ new tactics. Therefore in the long run I believe targeting certain ethnic groups will give false notions of security.
What is wrong with stop and search? Surely it just makes sense for police to be able to stop anyone they think might pose any sort of threat to our safety. I really can't believe that some people are yet again crying out 'racism' - what do these people want? Wouldn't you rather the police were empowered to get on with the fantastic job they have done so far - or must political correctness really win over national security/safety?
Nicky, Middlesex, UK
Police on the beat and stricter border controls - how ironic it takes an act of terrorism for the public's wishes to be granted.
Jo Kavanagh, Stansted, Essex
Surely any stop and search policy has to be ethnically neutral, even on the most basic practical grounds. We're dealing with people who are adept at manipulating others. They will be perfectly capable of getting a white drugs courier to carry a package with a timed bomb inside.
Ian Kemmish, Biggleswade, UK
I used to live three streets away and I am shocked at this. I am thankful for the police for their work. Being an Asian immigrant myself, I am happy to take the temporary inconvenience in exchange for a peaceful future.
I am one of those grumpy middle aged men who have been known to ask "What do we get for our taxes?" I feel my question has received a curt and decisive answer. Has any other police force in the world taken five suicide bombers alive? Could any other force have done it so quickly and so professionally? Our policemen have every right to feel proud of a job well done.
I feel heartfelt sadness for the victims of the London atrocities and also for the people of London. I would like to commend all the police services for their unstinted professionalism. And I pray for the young man who tragically and mistakenly lost his life.
Am I the only person who now believes that in order for the police to effectively be able to protect the public from suicide bombers, every police officer needs to be armed while out on the beat?
Guy Handscombe, Bedford, UK
In answer to Guy H's comments about arming the police force - no they shouldn't be armed! If you arm the police force, you arm the criminals. Arm them when absolutely necessary.
Keith, Zurich, CH
I am a Central London University student, using the trains every day. I feel much more "safer" with the extra police presence and have been impressed with speed at which these terrorists have been caught.
Amit Majevadia, Southgate, North London
I live in the area and have done all of my life. It feels really odd that there are people living amongst us who want to kill. With the Notting Hill carnival only a few weeks away, I hope it will be a time when we can all get back to enjoying ourselves again.
Nicky, West London
I am a resident of the estate in North Kensington. I have only just been allowed back into my flat after being escorted by a police officer. A lot of my neighbours, some of whom are very elderly, are very scared. There is a strange, almost surreal atmosphere and it's so unusual not to hear the sound of children playing outside.
Mark Stevens, North Kensington
I live very near to the latest Ladbroke Grove arrests and it sickens me that this very morning I might have bought bacon and eggs from the very shop where they bought different things.
Matt Kirschen, Ladbroke Grove, London
My train to work was swarming with police, seemed to be a lot of heavily armed police milling round London's stations. Saw a man being led away by police after being told at gun point to stop, as police wanted to search him.
Bert Chigley, London
I live in Notting Hill Gate round the corner from raid and I work next to Liverpool Street. Nowhere feels safe at the moment - the government needs to take strong action or I am moving country!
I hate to hear about this. One raid was in my dad's block and one two roads away from my mum's house. It is so scary and I want this just to stop.
Mickey Perkins, London
It is absolutely devastating to learn every day something terrible is happening in London. I live right outside Edgware Road station and work in High Street Kensington. At the moment I am getting to and from work on foot. I tried to use public transport but get very anxious when I see someone acting strangely or wearing a rucksack. One guy in the train had a walkman wire hanging out of his pocket and everyone left the carriage at the next stop.
Katherine Kharchuk, London
I work at Liverpool St and I'm finding it difficult coming here at the moment. Every time I use the train I'm more aware of people around me and what they are carrying. I don't want to have to live like this, its not fair.
J Stevens, London
My train to work this morning was 'arrested' by British Transport Police outside Loughborough for almost 2 hours. After clearing a carriage and questioning a man for some time, he was handcuffed and taken off the train. My journey to work, which normally takes under 2 hours, today took five and a half.
Brian Williams, Wirksworth, Derbyshire
I'm in Liverpool Street and we were all locked in the office and told not to go near the windows. All you could see was roads empty and taped off with police tape - very unnerving.
Rob Villa, London
I'm trapped in Tavistock Crescent. Police say I can leave my house but can't return. My father is now stuck outside the cordon and can't get back!
Mr JC Pandy, London
I was near Tavistock and heard the bang. I was here on the 7th and now feel like I am going to pieces. I think I may move home so I can be safe and alive.
Kentis Nghnn, London, UK
I live in Tavistock Crescent with Basing St just at the bottom of the road. It freaks me out the thought of someone I may have passed from time to time may have been capable of doing something like this. It is a very racially mixed area and I'm sure the community will very shocked at today's events.
Paul Moloney, North Kensington
My husband is currently in his office just near Liverpool Street station. It is currently closed and they aren't allowed out of the building and have been told to stay away from the windows.
I feel really odd that this is happening on my doorstep! They have clearly been hanging around the local area for quite some time. I most likely have walked past them in the street, perhaps even smiled at them. I am glad the police are around to keep things under control - it's better they are caught and dealt with now.
Vishal Vora, North Kensington
Have just heard through a work colleague that Liverpool Street area has been evacuated this afternoon and controlled explosion performed. Not sure if this is in connection with the two arrests made at Liverpool Street.
Lisa Regan, Moorgate, City of London
I have lived in W10 all my life. My son goes to school in W10, my mum lives off Dalgarno Gardens as do many of my friends. I can't believe these evil people are residing in the area! So many families, it's just unbelievable.
Becky, London, W10
I live in Notting Hill and am now worried that I might not be able to get home tonight if streets are still cordoned off until tomorrow.
C. Hartley, London, UK
Old Brompton Road, Queensgate and other streets in SW7 were closed for around 1½ hours and people told to stay inside by police. The cordon was cleared around 2pm.
Michael Pritchard, London
I play for a local football team, and our training ground is in Ladbroke Grove. It is very scary when something like this can happen on your doorstep. We have suspended training for the day and are going home to be safe.
Randy Wolff, Ladbroke Grove, London
I live in Tavistock Crescent and from my bedroom window I can see a group of police, a cordoning tape, and hear a chopper above. After a raid in Harrow Road last week I'm more and more alarmed that there are suspects within this area. Alarming.
Being From Notting Hill I am close to both Edgware Road and Shepherds Bush. I actually got off a bus this week because of someone acting strangely. I'm glad to see that the police and other services are doing everything they can to deal with this, even is someone has lost their life! I will not let this difficult time stop me from living my life!
Katie, Notting Hill, West London
I feel that the poor Brazilian man and the police officer who shot him are both the victims of these evil terrorists who are intent on causing death and destruction. Not only has a family lost a loved one, but I am sure it will have completely ruined the officer and family's life as well - he now has to live with what happened. The blame lies solely on the bombers whose actions have caused the need for a shoot to kill policy.
Sally, London, UK
I commend the police force in apprehending the bomb suspect without injury. But worry the tube shooting may politically handcuff the judgement of officers.
Chris Green, Duncan, Canada
The police need to use all means necessary to extract information out of the caught bomber in order to catch his accomplices.
Abu Labeebah, London
I'm so pleased that police have caught one of these men alive. One of the frustrations of suicide bombing is that the perpetrators never have to face up to their disgusting crime, and this man most certainly will. I suspect that life in a UK prison won't be quite the 'paradise' he had in mind, and I for one am unashamedly gleeful.
How is it so difficult to find these people? Are they being sheltered? It's time for all UK citizens to step forward and help
I live one road up from the bus bomber's mum and dad's house - I found out yesterday when reporters turned up. It just goes to show we don't know what is on our own doorsteps.
I don't understand the police. They shot an innocent person eight times and when it comes to the actual bomber they use a stun gun.
David, East London
I feel very proud of the way our security services are handling this and of the way that as a democratic nation, the truth behind the erroneous killing of the innocent Brazilian was so widely reported last week.
It will be interesting to see if they can get any information out of the suspect. Since he was willing to die for his cause, I am not sure how effective standard interrogation will be.
Sam, Alton, Hants
Perhaps we should all be a bit more observant and pay closer attention to what goes on in our neighbourhoods. Nosy neighbours peeping from behind net curtains may rightly be an object of derision but nevertheless a healthy interest in what neighbours are doing might act as a deterrent.
M. Wilson, UK
Despite the tragic shooting of the Brazilian last week, I still have to praise the police for the work they are doing in light of the extreme threat now facing this country. I was not in favour of the war in Iraq but innocent people cannot be blamed for politicians' decisions so I think people who want to kill innocents should face the harshest punishment.
Jayne Barratt, Birmingham
Although it was unfortunate that an innocent man was shot dead by police last week, it is important that the police remain vigilant and not allow incidents like this to shatter confidence.
I think the police may be jumping to conclusions and arresting anyone who fits a certain profile. They should be careful not to stir up cultural tensions and look to build relations with the community. This will be more effective in helping them conclude their investigation.
Khaled Arikat, London, UK
Someone asked why wasn't a Taser gun used last Friday? As an electronics engineer, I would say it would definitely set off a bomb. A Taser gun stuns by creating a large electric charge which could then trigger any detonating device. Sorry, a nice try but it's a non-starter.
Mark, Hemel Hempstead, UK
I am very proud of our police force. It makes me feel we are in good hands. What I am more worried about is the safety of our police force. They are in the frontline and possibly would be a close range of a suicide bomber. Are there ways to protect the police who are in the frontline?
Christina Spybey, London, UK
To Mr. Khan, while I appreciate your concern, it worries me that this only seems an issue when it's on your front doorstep. This is countrywide and with the threat to the innocent public - we all have to come together and defend our collective front doorstep. I am impressed by the speed of the police investigation and while very concerned about their actions when involved with Friday's shooting - I commend them on a brave and thorough job.
Rachael , London
In the current environment the police clearly need the ability to disable a suspect swiftly and temporarily with the prime aim of controlling the situation. It is equally important that the risk of undesirable side effects is minimised. I have every confidence that those responsible for procuring the taser gun and authorising its use have taken all this into account. However, given that the police have weapons like the taser at their disposal, when is a 'shoot to kill' policy ever justified?
Martin Herring, Bristol
I do hope the police have chosen to use the Tazer gun rather than a conventional firearm. I just hope the aren't pandering to the 'shoot him in the hand' brigade - these are dangerous times and thus require drastic measures. We cannot allow ourselves to be dictated to by liberalists and advocates of 'liberty' who attempt to undermine our security in the guise of political correctness.
Alan Taylor, Liverpool UK
I would give the police my full support in anything they have to do to stop these bombers, including a "shoot to kill" policy", providing that the public have been warned that we are in a maximum alert situation and a shoot to kill policy is in operation and anyone who does not stop or co-operate with the police will be shot. However, where possible, stun guns should be used.
Mrs Sylvia Lay-Flurrie,
The police and security services are doing an excellent work in very dangerous environment, we are in now. Unfortunately we are too quick to condemn them, when some thing goes wrong.
Mohammed Jamil, Birmingham, UK
I feel protected and reassured by the swift and decisive actions of the security forces. I am quite sure any impressionable youngsters who might have harboured notions about this being a cause worth taking up will now have a rethink.
I worked for the security services in Iraq, and there is absolutely no way of telling if someone is a bomber or not. The police made the right decision, however unfortunate, but they now have to live with that memory.
Darrell Jones, Warwick
Despite the fact that I think the police need to be very careful about the application of their shoot-to-kill policy, I've been very impressed by the speed and professionalism of the investigation itself. The use of a Taser here is also encouraging, although that may not have been practical in last Friday's incident.
Colin Wright, UK
The rapidity with which men have been arrested and the way the pieces have been put together speaks volumes for police intelligence. This will reassure the public and will also send a very strong signal to the terrorists that their path of violence is doomed to failure.
Pancha Chandra, Brussels, Belgium
Although the police have found a few people, I am still terrified. Everyone else is too and it will be a long time and take many more breakthroughs before we all feel safe again.
Neil Lithgo, Walthamstow, London
I couldn't believe it - I could see the 9th floor of Curtis House clear as day from the kitchen window of my old flat. You never know who your neighbours are these days.
It looks like the police have had a success after the dreadful incident last week. Welcome news! The authorities are overall doing a very impressive job and deserve the support of the public. The use of a taser weapon seems to point to lesson learned from the tragic death of an innocent man.
I hope the police aren't using taser guns instead of conventional firearms because of the tragic mistake made in killing the Brazilian man last week. The Government and the police must not downgrade their shoot-to-kill policy. The police deserve to ensure their own safety as they go about making the world securer for us.
The speed of the police investigation is very impressive. These people are obviously the tools of a bigger machine. Getting to the roots of the organisations that train, fund and recruit is going to be a much harder, longer more dangerous task.
Ian Paterson, Shepherds Bush
I would like to commend the police for the work they have done so far, working in what are extremely difficult circumstances. Those criticising the police should perhaps be reminded that they are working for the safety of everyone. Mistakes, such as the tragic shooting of the Brazilian gentleman are, unfortunately, a part of the price we must pay in the current climate.
Gillian, ex-pat, Germany
What is concerning me most is that following the arrests made in Leeds and now Birmingham, the location of these extremists seem to be countrywide. The police should be given as much power as necessary in all areas of the country to tackle the issues.
To John, Wembley: Tazers are great but you do have to get within about 12 feet of a suspect to use one. That's much closer than I'd like to get to a suspected suicide bomber. We don't realise how brave our police are.
The reason a tazer was not used last Friday is because it doesn't immediately incapacitate. It electrocutes, as its name would suggest, therefore allowing said suicide bomber to detonate his explosives. I think the police and security services have done a fantastic job since the first bombings; they have reassured the public at every opportunity and have seemingly identified the bombers exceptionally quickly.
I have nothing but the utmost pride in the way the police are moving on with the whole terrorist situation. One question I have is if a Tazer gun is used on a primed suicide bomber wouldn't that cause an explosion?
Despite last week's sad news, I think the security services are doing a first class job in dealing with this threat as swiftly as possible. I have a lot of respect for the police given the unenviable task that they are facing.
Andy Bird, Cheshire, UK
I believe the police and other agencies involved have done an excellent job thus far to prevent the inevitable attacks. However a firm stance with the current suspect, if properly identified would be essential.
Alexander Taylor, Liverpool
I'm really concerned about what has happened today in Birmingham. I live around the corner from the evacuation and it really concerns me that we are facing this on our own doorstep.
Mr Khan, Small Heath, Birmingham
I am glad this time the police appear to have made arrests without shooting anyone. This will help rebuild some confidence in them after the shooting of an innocent man last week.
Paul, London, UK
The taser gun is a good idea but only if it will stop innocent people being killed by the police. Why was this method not used last Friday?
John Agyeman, Wembley