Britain's anti-terrorism police are looking for three more people in connection with the discovery of the deadly poison ricin in a north London flat.

Only small traces of ricin were found in the operation - launched after a tip-off - but there are concerns an amount of poison could have been made at the flat and has been moved.

Tony Blair said the arrests showed the continued threat of international terrorism was "present and real and with us now and its potential is huge".

Is the UK prepared for a terrorist attack? Is Tony Blair's alert alarmist or sensible? How do we balance panic and vigilance?

Rear Admiral Richard Cobbold, director of the Royal United Services Institute answered your questions in a forum for the BBC Six O'clock News, presented by Manisha Tank.

Transcript

Manisha Tank:
Welcome to the Six Forum. A seventh man has been arrested as police continue their hunt for a potential cache of the deadly poison ricin. The initial arrests were made after traces of ricin were found in an innocuous looking flat in Wood Green in North London. Well, should we be worried and what's the Government doing to protect us - not just from ricin but from other potential terrorist threats?

Our guest, is Rear Admiral Richard Cobbold, Director of the Royal United Services Institute. He's an expert on troop deployments and military manoeuvres. He served in the last Gulf War as Assistant Chief of Britain's Defence Staff.

Richard, it's very good to see you. We have a lot of apprehensive people who've written into us and hopefully you can answer their questions.

We start with an e-mail from Jane Robinson, Valdosta, USA: I live in the US but will be taking my family with me on a trip to London for the next few days. We have been looking forward to this trip for a long time but I must admit I am a little worried about a visit to the city of London now.

Should Jane be worried?

Rear Admiral Richard Cobbold:
Well, I don't think so, particularly if she's going to the City of London because that seems better protected than the rest of London.

I think to put it in proportion, what Jane should be worried about is the traffic in London or some mundane danger that we face all the time. There's far more chance of being killed in a traffic accident than there is being killed by ricin or indeed any other terrorist activity at the moment.

Manisha Tank:
Going back to the ricin issue. Stephen, UK asks: Are we safe? How do you catch it? How do you know if someone has been affected by ricin?

Can you just tell with this what was the case of ricin being used that you can remember where somebody actually died?

Rear Admiral Richard Cobbold:
I think the last case of ricin being used was against a Bulgarian dissident in about 1979, called Georgi Markov. He was killed walking over a bridge in London. He was jabbed by an umbrella that had ricin impregnated in the tip of it by the Bulgarian secret police and he died a few days later. The hospital, at the time, was quite slow to identify that the toxin was indeed ricin. I don't think there's been any recorded case since then.

The symptoms that are seen tend to be rather like a nasty flu and then after a couple of days it degenerates into a rather nasty gastro-enteritis with bleeding diarrhoea, bleeding in your lungs and your eyes get extremely sore and have pus and then it gradually it continues to deteriorate and you get multi-organ failure and die.

But I think the point is that you don't catch it in the sense of a disease - it's a toxin. It's a biologically derived poison and you can either get the effects of it by having into the bloodstream - as Georgi Markov did - or else inhaling it, if it's sprayed in your direction in an aerosol. So if it's just on your skin, you'd be most unlikely to get it. If you do get ricin liquid on your skin, then you wipe with a cloth and a separate solution. It's a very difficult weapon to use. It's a weapon to use against one person. It's not a weapon that you'd use if you were trying kill a lot of people. So I do think it's not really a weapon of choice for terrorists.

Manisha Tank:
Alex Stephens, Sutton, Surrey What is the risk of ingestion if the toxin (ricin) were added to the local water mains?

Rear Admiral Richard Cobbold:
I think if it was in the water supply it would be diluted so much that it would be very difficult to ingest a sufficient concentration. Although it is extremely dangerous if you take two or three milligrams of it then that would kill you. But to get a few milligrams of a concentrated poison into the water supply of say London would be extraordinarily difficult.

Manisha Tank:
Richard Thompson, Leeds: If there was a biological attack, would we be as equipped as the USA to deal with it? If not, why?

Rear Admiral Richard Cobbold:
I depends what we mean by a biological attack. At the lower end we have the distress about anthrax in London and elsewhere in the autumn of 2001 which were not real attacks but they were scares coming over after the real anthrax attacks in the United States.

Although there are enormous psychological effects but anthrax is a powder and can be treated as a powder. It's not a disease - it's not contagious in the normal sense. So in that case, it's a matter of cordoning off an area, cleaning it, screening everybody and I think we're very adequately protected against that sort of localised attack.

The particular doomsday scenario that had been talked about in the media is the possibility of smallpox because it does seem likely that there is smallpox somewhere out there - at least there is a potential for terrorists to get hold of it. Smallpox, if released into the public which hadn't got immunity through vaccination, could spread very quickly.

I understand that the United States has got a vaccination programme waiting to go. Enough vaccine has been bought for every member of the United States population. That is not so over here, although a large number of vaccines have been bought - not enough for everybody. I think that the action that would be taken by the authorities would be to really quite ruthlessly contain an outbreak insofar as is possible by putting a boundary around and stopping people mixing and trying to just reduce the epidemic by that sort of means. Of course there is a considerable ability to treat smallpox symptoms in hospitals in isolation wards.

Manisha Tank:
Smallpox was a subject I wanted to get on to. We had questions from Janet Hillier in Thames Ditton and Fiona who were asking about those very issues. Janet added that there was some controversy over whether the Government had actually obtained the correct smallpox vaccine. Is that situation now cleared up?

Rear Admiral Richard Cobbold:
As I understand it, the best estimate of the smallpox vaccination has been obtained. Although to some extent, it's a little bit like flu vaccines - a flu vaccine you have to guess in advance what sort of flu virus you are going to have to vaccinate against and you have to do that about 18 months before the virus is likely to strike because that's the way an epidemic spreads. So the best estimate has been made on the smallpox but it won't necessarily be entirely right. Even if it is right now, it wouldn't necessarily always be right into the future.

In broad terms, I think the Government has done a lot. Now it could perhaps do more, it could start a vaccination programme but that would be a matter of judgment whether that would be a sensible thing to do or whether it is an excessive thing to do. I think it is still a matter of keeping things in proportion. There are 3,000 people killed every year in road traffic accidents. In Africa an enormous number of people are killed in various ways by machetes and machetes after all are agricultural implements. So biological weapons have not on the whole proved major killers for a very long time.

Manisha Tank:
Sam Keith, Bedford: Do you say the Government is focusing too much on the threat of al-Qaeda and should focus more on small terrorist organisations?

Emily Walsh, London, UK: What can we bring to bear from our experiences with the IRA in pre-empting terrorist actions?

Rear Admiral Richard Cobbold:
We certainly learnt a lot from the IRA. I think there was a difference between the IRA which are intentionally political terrorists and they have political aims and therefore they were to some extent limited by the fact they wanted to achieve those aims As an example of that they were limited and they didn't go beyond a certain level of outrage and there was always the possibility of negotiation with them - so that's the IRA.

We've learnt a tremendous lot about countering terrorism from 30 years experience with the IRA. The emergency in Ulster started in 1969 and didn't really ease away until 1999 so that was 30 years of pretty hard won, bloodstained experience.

Now the difference with al-Qaeda is that it is an extremist organisation that is very loose - it sometimes is not even to be grouping or a linkage - it's an idea. It is an idea that people who are broadly sympathetic to that idea can tune into and get encouragement, guidance, technology, they can get help and so it's very difficult to counter that organisation. But also, as we saw in the suicide bombers, particularly those flying the aircraft into the Twin Towers in New York, they are essentially suicide bombers. Now it is very difficult to negotiate with people who believe that they will be going to a better place by committing suicide and you can't appeal to their better nature or still less to the fact that they're getting a political aim met by cooperating with the government.

Manisha Tank:
On the question of Iraq, Marco, London asks: Has the UK considered the increased risk of terror attacks by running off to wage a completely unnecessary war?

There is obviously a great wall of fear now amongst the public that we will see repercussions if we starting massing troops on the border with Iraq.

Rear Admiral Richard Cobbold:
Let's first deal with ricin comes from. I think people have said Algeria and Afghanistan because that's where traces of ricin have been found in a Taleban, al-Qaeda hideout in Afghanistan and of course in north London just recently.

Ricin is potentially easy to acquire. If you eat eight castor oil pods raw you will ingest enough ricin to kill you, in the same way as all sorts of other toxins you can get from poisonous plants. So ricin is itself not difficult - it is a bi-product of the creation of castor oil. So the fact that people are making it is nothing very terrible. A lot of people are making it and disposing of it quite properly in their normal business. So that itself is not a great problem.

There's a very important point about Iraq and that is that the linkage, in my view, between what one might call the war on terror and a potential conflict in Iraq - the linkage is not all that strong. Saddam Hussein is a secular despot - an appalling dictator who really is very bad. Al-Qaeda is a religious extremist grouping. The two organisations don't really have any natural link at all.

They may have a link of convenience - they may find it tactically convenient to cooperate from time to time. But I think it's probably wrong to assume that there's a real idea that this is an arm and leg on the same body. I really don't think that that is true. They may find it useful to exchange equipment, exchange tactics but they are not the same organisation and I think the suggestion that by going into Iraq we are exposing ourselves to additional threat from al-Qaeda is probably not correct. Although if we are seen to be weakened as a result of military action in Iraq that might be seen as an opportunity for al-Qaeda to press home an attack elsewhere. The link is not strong.

Manisha Tank:
Richard while you've been talking our Online viewers have actually been voting and they're letting us know how they feel about the terrorist threats in the United Kingdom - 55% of our Six Forum viewers are saying that we do not feel at risk. But that's not a scientific poll Richard, it's just an indication of how people are feeling. Do you think they're right or should we be more vigilant perhaps?

Rear Admiral Richard Cobbold:
The Government are saying they should be vigilant but not frightened. I think that's probably very good advice although vigilance is really against any form of terrorism. To be absurd I don't think it's reasonable to look with suspicion to every man you see coming towards you carrying an umbrella and it's very difficult to see how you can actually be alert to the possibility of ricin.

But what you can do undoubtedly is be alert to people who are talking about terrorism, people who are suspiciously, people who are asking perhaps too many questions about important people in the Government. That's the sort of the thing that gives you an indication, some information, that things are going wrong.