Terror attack on Western city 'matter of time' - M15

A terror attack on a major Western city using chemical, biological, radiological or nuclear (CBRN) technology is "only a matter of time," the head of Britain's domestic intelligence service MI5 said yesterday.

Eliza Manningham-Buller said violent extremists were becoming more sophisticated in developing such non-conventional threats thanks to help from "renegade scientists."

"We are faced with the realistic possibility of some form of unconventional attack. That could include a CBRN attack," she told a conference in London on countering terrorism.

"Sadly, given the widespread proliferation of the technical knowledge to construct these weapons, it will only be a matter of time before a crude version of a CBRN attack is launched at a major Western city," she added.

The MI5 head was not referring to any specific new threat and was only repeating previous warnings from intelligence sources. But such blunt words in public from a senior secret service official are rare.

Manningham-Buller, who took over MI5 late last year as only the second-ever woman head, said intelligence showed rogue scientists had been helping groups including al Qaeda, blamed for the September 11 attacks against the United States.

"We know that renegade scientists have cooperated with al Qaeda and provided them with some of the knowledge they need to develop these weapons," she said, without saying where the scientists were from.

As the closest ally of Washington, Britain sees itself as a likely target and last month erected a concrete barrier round parliament in the latest high-profile security measure.

Osama bin Laden's al Qaeda and groups linked to its network have, however, carried out no successful bomb attacks on Western soil since September 11, 2001, focusing instead on easier targets in Kenya, Bali and, recently, Saudi Arabia and Morocco.