BBC political editor Andrew Marr said "very senior sources" in Whitehall had virtually ruled out the possibility of finding the weapons.

They believe they did exist - but were hidden or destroyed by Saddam Hussein before the war.

Downing Street said earlier that the prime minister stood by what he told the Commons on Tuesday - that he was convinced that evidence of Iraq's weapons programme would be found.

Does it still matter if weapons of mass destruction are found? Tell us what you think

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