WMD attack inevitable

Speaking to Britain's Daily Telegraph newspaper, Henry Crumpton, the US State Department coordinator for counter-terrorism, said he feared the threat from biological weapons was rising.

"I rate the probability of terror groups using WMD as very high," he was quoted as saying. "It is simply a question of time.

"It is not just the nuclear threat that bothers me. I think, if anything, the biological threat is going to grow."

He said a biological attack would pose far greater problems than an explosion containing radioactive material.

"As catastrophic as a nuclear attack would be, it would be self-contained," Crumpton told the newspaper. "But if you look at a worst-case scenario for a biological attack, it would be difficult to determine whether or not it was a terrorist attack, and it would be far more difficult to contain."

He said that after the war in Afghanistan, the United States had found evidence of an al-Qaeda plot to develop anthrax for use against the West.

He added that US forces and their allies had disrupted al-Qaeda and its leader Osama bin Laden since the September 11, 2001, attacks in the United States.

"They can't communicate with their supporters unless the odd courier breaks through. They can't get access to money and things like that. We have made life very difficult for them."