The suggestion by the US Defence Secretary, Mr Donald Rumsfeld, that Iraq might have destroyed chemical and biological weapons before the war comes as scepticism rises in the US Congress and abroad about whether there were any to be found in the first place. Conor O'Clery, reports from New York
Most Americans continue to accept the administration's moral basis for the war, that Saddam Hussein possessed banned weapons. A poll this week shows that 82 per cent believe that the failure to find them is more likely because they were destroyed or moved, while only 10 per cent said they believed there were no weapons in the first place.
Leading Senate Democrats, however, have accused the Bush administration of either exaggerating the threat posed by Iraq or using faulty intelligence.
Senator Joe Biden of Delaware, the senior Democrat on the Senate Foreign Relations Committee, has said the administration "hyped" Iraq's potential for developing nuclear arms and for using other weapons of mass destruction.
Senator Jay Rockefeller of West Virginia, the Senate Intelligence Committee's senior Democrat, said he felt that the intelligence cited about Iraq's weapons programme was not as sound as he had been led to believe.
Congress must determine whether the administration "intentionally overestimated" or "just misread it" and that in either event, "it's a very bad outcome".
Some Republican lawmakers have also expressed concerns.
Senator Pat Roberts of Kansas, the chairman of the Intelligence Committee, said there was no doubt that Iraq had banned weapons, but if not found "basically, you have a real credibility problem".
The failure to find banned weapons in the seven weeks since Baghdad fell has strengthened the case of nations that declined to join the US-led coalition. Canada's Prime Minister, Mr Jean Chretien, said it vindicated his view that more time for inspections was needed, and Russia's President, Mr Vladimir Putin, recently asked pointedly: "Where are they?"
On Monday, the chairman of the Joint Chiefs of Staff, Gen Richard Myers, said he believed it was "just a matter of time" before US forces found what they were looking for and that the prospects would increase as they continued to capture senior members of the former regime.
Mr Rumsfeld said however the next day: "It is also possible that they decided that they would destroy them prior to a conflict."
Pentagon officials have said that his remark, in reply to questions after a speech in New York, was consistent with past explanations. Two weeks ago Maj Gen David Petraeus, commander of the Army's 101st Airborne Division in northern Iraq, first suggested that banned weapons might have been destroyed.
However critics point to the difficulty of destroying or hiding the vast amounts allegedly available to Saddam, which, the US Secretary of State Mr Colin Powell told the United Nations on February 5th, included 25,000 litres of anthrax and between 100 and 500 tonnes of chemical weapons and the means to deliver them.
In an interview in April with NBC news Mr Bush acknowledged: "There's going to be scepticism until people find out there was, in fact, a weapons of mass destruction programme."