Former MI6 chief warns of 'dreadful' terror threat

The former MI6 chief Sir Richard Dearlove said that we must now expect a biological, chemical, radiological or even nuclear attack because intelligence showed that was what al-Qa'ida and its linked organisations had developed an interest in.

He said that the July 7 bombings were "locally" planned and executed, and that we were "misleading ourselves" if we thought this was the worst we could expect.

The greater threat, said Sir Richard, was a "strategic event" in which terrorists would make use of technology available on the internet.

"There's some complacency about the nature of the threat and we are misleading ourselves if we think this is the worse it can be ... There are much more dreadful events that could occur."

He told a seminar on the Government's counter-terrorism measures, organised by international law firm Ashursts, that rapid advances of genetic manipulation of viruses meant we "had to believe that they will do something extremely frightening". But he believed a nuclear attack, such as a dirty bomb, was "low risk" because of the difficulty for terrorists to obtain fissile material.

He told the audience of lawyers and human rights experts the measures in the Terrorism Bill were necessary because "we have to give the Government the best chance of preventing such an event".