In his presentation before the U.N. Security Council on Feb. 5, 2003, Secretary of State Colin L. Powell said "firsthand descriptions" of the mobile bioweapons fleet had come from an Iraqi chemical engineer who had defected and is "currently hiding in another country with the certain knowledge that Saddam Hussein will kill him if he finds him."

The claims about the mobile facilities remain unverified, however, and now U.S. officials are trying to get access to the Iraqi engineer to verify his story, the sources said, particularly because intelligence officials have discovered that he is related to a senior official in Ahmed Chalabi's Iraqi National Congress, a group of Iraqi exiles who actively encouraged the United States to invade Iraq.

Powell also cited another defector in his speech, an Iraqi major who was made available to U.S. officials by the INC, as supporting the engineer's story. The major, however, had already been "red-flagged" by the Defense Intelligence Agency as having provided questionable information about Iraq's mobile biological program. But DIA analysts did not pass along that cautionary note, and the major was cited in an October 2002 National Intelligence Estimate on Iraq and was mentioned in Powell's speech, officials said.

The administration's handling of intelligence alleging the existence of mobile bioweapons facilities has become part of several broad investigations now underway into the intelligence community's faulty prewar conclusions that Hussein possessed weapons of mass destruction. The Senate and House intelligence committees are conducting probes, as are the CIA and a commission appointed by President Bush.

The investigation of claims about mobile weapons labs, however, does not just cover prewar intelligence, but also includes the performance of the intelligence community well after the invasion.

U.S. intelligence officials now describe as hasty and premature the May 28 public claim by the CIA and the DIA that two semitrailers discovered in Iraq in April were most likely part of the bioweapons fleet. [ed. Ya think?!]

The highly publicized claim, one official said, was triggered by a May 11 NBC News broadcast featuring David Kay, then a network analyst in Iraq, who would later become the chief U.S. weapons inspector there. Kay was shown next to one of the found vehicles with a chemical officer from the Army's 101st Airborne Division who, on camera, agreed that the semitrailer was equipped to make biological weapons.

Days later in Washington, the CIA and the DIA put out an unclassified white paper that said the production of biological agents "is the only consistent, logical purpose for these vehicles." The next day, Bush said the trailers showed that the United States had found former Iraqi president Hussein's prohibited weapons. "For those who say we haven't found the banned manufacturing devices or banned weapons, they're wrong," Bush said. "We found them."

Since then, intelligence analysts and Kay, a nuclear-weapons expert with little experience with biological weapons, have said the trailers were probably not used in a bioweapons program. Kay has said he believes the trailers were likely used to produce hydrogen for weather balloons.

CIA Director George J. Tenet is expected to face questions today about the alleged mobile bioweapons fleet and other elements of Hussein's weapons of mass destruction programs when he appears in a closed session of the House Permanent Select Committee on Intelligence. He appeared before the Senate intelligence committee in closed session yesterday.

The Senate committee has drafted a highly critical report on the prewar intelligence of the CIA and other agencies. The problems uncovered in the mobile-bioweapons area illustrate what the panel has found in the collection and analysis of information about Iraq's chemical and nuclear programs.

Tenet has already disclosed that the agency has changed some procedures as a result of the problems discovered by its reviews. For example, there are new procedures on how to handle material flagged as coming from questionable sources, such as the Iraqi major. CIA analysts are now to be given more information from the CIA's operations division to help them assess the reliability of those who provide information.

CIA officials reviewing the bioweapons intelligence say that the engineer who provided the original tip never dealt directly with U.S. intelligence agencies, and that he passed along the information through a foreign intelligence service, which they refuse to name. U.S. intelligence analysts did not know his name before the war, relying entirely on foreign officials to vouch for his credibility, according to a former CIA employee as well as administration and congressional sources.

U.S. officials are trying to interview him, sources said, but the foreign intelligence service that originally forwarded his information has declined to produce him for questioning.

The May 28 white paper on the semitrailers is also under scrutiny. A retired senior intelligence official said recently that the unclassified paper was hastily put together before a full, classified analysis was written and circulated within the intelligence community.

The paper was produced so quickly, one senior administration official said, because of Kay's May appearance on NBC, in which he pointed to one semitrailer and said: "This is where the biological process took place . . . literally, there's nothing else you would do this way in a mobile facility."

Kay said he returned to Iraq as a U.S. weapons inspector a month after his television appearances and found that the DIA analysts who had inspected the trailers disagreed that they were part of mobile biological-agent production plants. By January, Kay had reassessed the matter, saying publicly that the "intelligence consensus" was that the semitrailers probably were for making hydrogen, not biological agents.

Administration officials continued to describe the threat posed by Hussein's mobile biological-weapons facilities.

On Jan. 22, Vice President Cheney told National Public Radio that Hussein had "spent time and effort acquiring biological weapons labs" and that the semitrailers "were, in fact, part of that program." He called the trailers "conclusive evidence, if you will, that he [Hussein] did in fact have programs of mass destruction."

On Feb. 24, Tenet told the Senate intelligence committee that there was "a big debate" about the trailers among CIA analysts "who still believe that they were for" bioweapons, and CIA and DIA analysts "who have posited another theory . . . and we haven't wrestled it to the ground yet."

Tenet said he had talked to Cheney and learned that his January statement was based on "an older judgment." © 2004 The Washington Post Company