Hans Blix, the former chief UN weapons inspector in Iraq, has accused Tony Blair of overstating the threat posed by international terrorism.

Dr Blix also said that the United States and Britain had acted like "witch hunters" in their insistence that Saddam Hussein’s regime had weapons of mass destruction.

He told the BBC’s Breakfast with Frost programme: "I think we still overestimate the danger of terror. There are other things that are of equal, if not greater, magnitude, like the environmental global risks."

Meanwhile, former chief of the defence staff, Lord Boyce, told the Observer that he had "required a piece of paper saying it was lawful" before allowing British troops to go to war in Iraq.