Powell was quizzed about the matter on a radio program after the New York Times reported Thursday on an internal document in which the State Department declared it was too early to determine whether the trucks proved anything.

Powell insisted again Friday that State Department analysts "do not disagree" with their counterparts at the Central Intelligence Agency and the Defense Intelligence Agency who were on the scene, examined the trucks and concluded that they were mobile biological warfare facilities.

But the State Department analysts "are not entirely sure yet" and "would like to see more analysis done," Powell said, adding that a request to that effect was sent to the CIA in a memo.

"A month has now passed since that memo. My guys would still like to see more data," Powell said on National Public Radio's "All Things Considered" program.

However Powell also took pains to express his confidence in the CIA's "opinion".

"There will always be, you know, different judgments and opinions in this business, and you essentially have to have somebody who makes the decision. And the person is the Director of Central Intelligence George Tenet.

"Will we continue to look for more information to reinforce our opinion? Sure, we will," he added.

"We're still looking at it, but I'm fairly confident of the Director of Central Intelligence's judgment."

Despite the revelation of doubters at the State Department, the White House has stuck by its claim that the tractor-trailers are solid proof that Saddam Hussein was trying to develop banned arms.

"The experts have spoken and the judgment of the experts is very clear on this matter," White House spokesman Ari Fleischer said Thursday.

President George W. Bush based his justification for the US-led war on his contention that Iraq possessed such weapons and so threatened US security.

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