merican and British intelligence analysts with direct access to the evidence are disputing claims that the mysterious trailers found in Iraq were for making deadly germs. In interviews over the last week, they said the mobile units were more likely intended for other purposes and charged that the evaluation process had been damaged by a rush to judgment.

"Everyone has wanted to find the 'smoking gun' so much that they may have wanted to have reached this conclusion," said one intelligence expert who has seen the trailers and, like some others, spoke on condition that he not be identified. He added, "I am very upset with the process."

The Bush administration has said the two trailers, which allied forces found in Iraq in April and May, are evidence that Saddam Hussein was hiding a program for biological warfare. In a white paper last week, it publicly detailed its case, even while conceding discrepancies in the evidence and a lack of hard proof.

Now, intelligence analysts stationed in the Middle East, as well as in the United States and Britain, are disclosing serious doubts about the administration's conclusions in what appears to be a bitter debate within the intelligence community. Skeptics said their initial judgments of a weapon application for the trailers had faltered as new evidence came to light.

Bill Harlow, a spokesman for the Central Intelligence Agency, said the dissenters "are entitled to their opinion, of course, but we stand behind the assertions in the white paper."

In all, at least three teams of Western experts have now examined the trailers and evidence from them. While the first two groups to see the trailers were largely convinced that the vehicles were intended for the purpose of making germ agents, the third group of more senior analysts divided sharply over the function of the trailers, with several members expressing strong skepticism, some of the dissenters said.

In effect, early conclusions by agents on the ground that the trailers were indeed mobile units to produce germs for weapons have since been challenged.

"I have no great confidence that it's a fermenter," a senior analyst with long experience in unconventional arms said of a tank for multiplying seed germs into lethal swarms. The government's public report, he added, "was a rushed job and looks political." This analyst had not seen the trailers himself, but reviewed evidence from them.

The skeptical experts said the mobile plants lacked gear for steam sterilization, normally a prerequisite for any kind of biological production, peaceful or otherwise. Its lack of availability between production runs would threaten to let in germ contaminants, resulting in failed weapons.

Second, if this shortcoming were somehow circumvented, each unit would still produce only a relatively small amount of germ-laden liquid, which would have to undergo further processing at some other factory unit to make it concentrated and prepare it for use as a weapon.

Finally, they said, the trailers have no easy way for technicians to remove germ fluids from the processing tank.

Senior intelligence officials in Washington rebutted the skeptics, saying, for instance, that the Iraqis might have obtained the needed steam for sterilization from a separate supply truck.

The skeptics noted further that the mobile plants had a means of easily extracting gas. Iraqi scientists have said the trailers were used to produce hydrogen for weather balloons. While the white paper dismisses that as a cover story, some analysts see the Iraqi explanation as potentially credible.

A senior administration official conceded that "some analysts give the hydrogen claim more credence." But he asserted that the majority still linked the Iraqi trailers to germ weapons.

The depth of dissent is hard to gauge. Even if it turns out to be a minority view, which seems likely, the skepticism is significant given the image of consensus that Washington has projected and the political reliance the administration has come to place on the mobile units. At the recent summit meeting with President Vladimir V. Putin of Russia, President Bush cited the trailers as evidence of illegal Iraqi arms.