The American Defence Secretary, Donald Rumsfeld, has said that Iraq may have destroyed all of its weapons of mass destruction before the war.
Mr Rumsfeld also confirmed that the United States military may have found two mobile biological weapons laboratories.
It is the closest the Bush administration has yet come to acknowledging the possibility that no actual weapons of mass destruction may be discovered in Iraq.
In a speech in New York, Mr Rumsfeld said he did not know why such weapons had not been used by Saddam Hussein against invading forces.
He also pointed out that many suspected sites had still to be investigated.
Mr Rumsfeld also warned Iran not to try to interfere in Iraqi affairs. He said the US would not tolerate such a development.
