A CLAIM by Tony Blair that “several hundred” active terrorists are plotting or threatening an attack in Britain has been challenged by senior security officials. The Prime Minister said that terror suspects all fell outside the existing powers of the police and courts to prosecute them, which was why the new “control orders” were required.

“There are several hundred in this country who we believe are engaged in plotting or trying to commit terrorist acts,” Mr Blair told Radio 4’s Woman’s Hour.

A Downing Street official said Mr Blair’s claim was based on the few hundred people being monitored by the security services, some of whom would be subject to the new control orders. However, one senior security source told The Times that the figures were based on numbers from MI6 of people who travelled to training camps in Afghanistan and Pakistan, prior to September 11.

Of that group of 200 or so, only 40 to 50 were regarded as a “moderate” or “serious” threat, and of that group up to 15 had disappeared from Britain altogether. That left around 25 or 30 who are known to be in Britain, with some of those in prison in Belmarsh.

The source said the Prime Minister’s estimates of the scale of the terrorist threat was sloppy. “It is irresponsible and likely to scare people unnecessarily,” the source said.

However, he added that he was in no doubt that there would be an attempt to stage a serious terrorist attack, using a dirty bomb, with London the probable target.

Mr Blair’s estimate that several hundred terror suspects were at large also raised eyebrows at Scotland Yard. Detectives said three years ago that they were concerned at the number of Muslim fighters slipping into Britain from Afghanistan and Chechnya, but suggested that several hundred had since made their way home.

The Prime Minister receives regular briefings from Eliza Manningham-Buller, the head of MI5, and also from the Commissioner of the Metropolitan Police. Neither has publicly talked about “several hundred” terrorist activists.

Charles Clarke, the Home Secretary, added further confusion when he said Mr Blair was referring to the 700 cases where police had already taken action, whether in the form of questioning or surveillance.

Mr Clarke had been pressed in the Commons debate on the Anti-Terror Bill to explain how his assessment that new powers to place suspects under house arrest would only affect a small number of cases with the Prime Minister’s claim that several hundred suspects were actively plotting attacks.

• Airline passengers travelling to and from the United States are to be banned from carrying cigarette lighters on planes from April 14 (Ben Webster writes). Smokers will be forced to use matches if they want to light up beyond the security checkpoint at airports.

  Lighters are already banned from checked luggage. The ban follows concerns raised by US senators over the case of Richard Reid, who tried to ignite explosives in the heel of his shoe aboard a Paris-to-Miami flight in December 2001. Security officials believe that if he had used a lighter rather than striking a match he might have succeeded in blowing up the plane.

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