London: Spy chiefs fear that there are more than 20 terrorist plots underway in Britain. Police and the security services believe that the previous estimate of 20 UK-based terror conspiracies, inadvertently revealed three weeks ago by John Reid, the Home Secretary, represented a "modest assessment" of the threat.
The number of terrorist suspects believed to be operating in Britain is now more than 1,200, almost 400 more that the figure revealed in last month's Intelligence and Security Committee report into July 7 Tube attack, last year.
Whitehall sources have also revealed that the government believes it is only a matter of time before terrorists launch a devastating chemical, biological, radiological or nuclear (CBRN) attack against a Western capital, such as London.
The warning comes just three weeks after police stormed the home of two brothers in east London in the mistaken belief that they were making a chemical bomb. It also follows concern among members of Britain's intelligence and security hierarchy that if a CBRN attack took place in London it could have disastrous effects on the British economy and severely damage those of Europe and America.
It has also emerged that the police were warned about the activities in West Yorkshire of the 7/7 bombers, almost two years before the suicide attacks.
Whitehall officials said that the 9/11 attack "freed the mind'' of intelligence agencies analysing the capabilities of terrorism and it would be "reckless'' to underestimate the "capability and intent" of terrorist groups, such as Al Qaida.
In a speech in June 2003, Dame Eliza Manningham-Buller, the director general of MI5, said that Al Qaida had the technical capability to make an "unconventional weapon" a description seen as referring to a "dirty bomb'' or a CBRN attack.
The threat is also underlined by claims by Osama Bin Laden, who referred to the existence of such devices on several occasions. In November 2001, he said that "if America used chemical or nuclear weapons against us, then we may retort with chemical and nuclear weapons. We have the weapons as a deterrent."
In a June 2002 article, Sulaiman Abu Gaith, the Al Qaida spokesman, also said: "It is our right to fight the Americans with chemical and biological weapons."