A 400-member American team, tasked with searching Iraq for military equipment, has been withdrawn from the country.
The move came as an influential Washington think tank published a report that concludes that senior US administration officials pressured intelligence officials to make a stronger case for war on Iraq.
According to some US government officials, the withdrawal of the Joint Captured Materiel Exploitation Group was a sign that the Bush administration has lowered its expectations of finding hidden weapons of mass destruction in Iraq.
The move comes as an independent report by a Washington think tank, the Carnegie Endowment for International Peace, suggested that US intelligence officials came under government political pressure to make a stronger case for war against Iraq.
Report author Joseph Cirincione told CNN: "We looked at the intelligence assessment process and we have come to the conclusion that it is broken.
"It has now become deeply politicised... it is very likely that intelligence officials were pressured by senior administration officials to conform to the threat assessment of pre-existing policies."
He said a threat assessment published by the Bush administration in the run-up to the war was "strikingly different" from previous analyses.
He said Iraqi weapons programmes were "crippled" by years of sanctions and US air strikes.
Mr Cirincione, whose think tank opposed the war, called for an independent inquiry into the report's findings.
Meanwhile, a 1,400-strong CIA-led Iraq Survey Group is continuing to hunt Iraq for the weapons of mass destruction which were the justification for war.
Among that team is a group specialised in disposing of chemical and biological weapons, but one group member told the New York Times they were "still waiting for something to dispose of".
The White House and Pentagon hope to find signs of possible weapons dumps among a massive collection of seized Iraqi documents, currently being stored in Qatar.
Many of the papers are still to be translated.
The developments come after new reports yesterday that Iraq may have destroyed
its biological weapons as early as 1991.
The Washington Post has reported that investigators had found no evidence of weapons dating back to the first Gulf War, or advanced weapons programmes in the years following that conflict.
It also repeated claims made last year that weapons scientists and engineers told Saddam that programmes were more advanced than they actually were.
Programme managers apparently exaggerated their successes to appease the
dictator, or to advance their careers.
Last year, David Kay, who is leading the Iraq Survey Group, said his team had
so far made no discoveries of actual weapons of mass destruction.
But he said there was evidence that Saddam's regime was attempting to develop
such weapons. Mr Kay said last month that he may leave his post earlier than was first
expected.
Intelligence officials insist that the search for weapons will go on.
Stuart Cohen, the vice chairman of the National Intelligence Council said in
an interview on Tuesday: "We worry about what may have happened to those
weapons.
"Theories abound as to what may have happened," he told ABC.
He added: "It is too soon to close the books on this case."
PA