Chemical terror gang quiz

Scotland Yard has uncovered a major terror plot after discovering residue of a lethal chemical weapon in a London flat.

The deadly chemical agent Ricin was recovered in a raid on a flat in Wood Green by the anti-terrorist squad and six people, who are believed to be of North African origin, were arrested at the address. One woman who was also arrested has been released.

Police sources emphasised that they have recovered only a residue of the chemical but fear that more of the substance is still missing.

The dramatic development was revealed at a hastily called press conference at New Scotland Yard this afternoon, given by Assistant Commissioner David Veness, the head of anti terrorist operations in the UK, and the Deputy Chief Medical Officer Dr Pat Troop. Mr Veness said six men, aged in their late teens, twenties and thirties, had been arrested at addresses in north and east London in the early hours of Sunday.

Mr Veness said a quantity of material and items of equipment were found at residential premises in Wood Green where one of the men was held. The seizure is a terrifying new development in the escalating war on terrorism. Despite recent reports of chemical plots no actual chemicals themselves have been found. This is the first such discovery of its kind.

The arrests have been kept secret until today when scientists revealed the positive results of tests. Police fear that a much larger quantity of the poison has been manufactured in a home-made laboratory at a premises in Wood Green.

Doctors, hospitals and other health services throughout the country have been alerted to the effects of the deadly agent.

Bulgarian dissident Georgi Markov was reputedly killed in London in 1978 when he was stabbed with a poison-tipped umbrella, which was used to put just 500 mg of ricin into his bloodstream.

Senior police officers called in health officials and other top-level experts to Scotland Yard today for urgent briefings.

There is no evidence of a specific plot against a particular target.

One police source said: "This is a new development and we would urge people to be extremely vigilant."

Today's arrests will underline the worst fears of senior Government figures charged with preventing this kind of terrorist attack.

Senior sources warned last year that Britain faced a real threat of terrorist attacks against soft targets causing huge civilian casualties.

They also said the Government was facing up to the view that a determined terror group will "sooner or later" get through even the most organised defences.

However, they believed that conventional bomb attacks like the Soho bombing - which killed a large number of people with relative simplicity - would be the most probable means used by the fanatics.

Chemical or biological attacks were certainly possible, but far less likely.

These arrests may show that the terrorists - who may or may not belong to al Qaeda - could have a higher level of sophistication than first believed. Whitehall sources revealed then that in al Qaeda camps in Afghanistan many recruits were being trained in rudimentary chemistry, with a view to stage terrorist attacks of this kind at a later stage.

British intelligence is sifting up to 150 reports per day linked to international terrorism. The data was said to be "very fragmentary".

In Whitehall, it is accepted that so-called "postcard targets", such as Big Ben are high on al Qaeda's list. But Whitehall sources stress that the notion of a terrorist detonating a "nuclear backpack" was still remote.

Last month, seven men were seized by anti-terrorist detectives in dawn raids in London and Scotland. Four were held at an address in west London and another three in Edinburgh.

All were of North African origin and in their early thirties and were detained under the Terrorism Act 2000.