Saturday, May 13, 2006; 12:03 PM

-- A year after Bush administration claims about Iraqi "bioweapons trailers" were discredited by American experts, U.S. officials were still suppressing the findings, says a senior member of the CIA-led Iraq inspection team.

At one point, former U.N. arms inspector Rod Barton says, a CIA officer told him it was "politically not possible" to report that the White House claims were untrue. In the end, Barton says, he felt "complicit in deceit."

Barton, an Australian biological weapons specialist, discusses the 2004 events in "The Weapons Detective," a memoir of his years as an arms inspector, being published Monday in Australia by Black Inc. Agenda.

Much sought after for his expertise, Barton served on the U.N. Iraq arms inspection teams of 1991-98 and 2002-03. After the U.S. invasion, he was an aide to chief U.S. inspector Charles Duelfer.

The Washington Post reported last month that a U.S. fact-finding mission confidentially advised Washington on May 27, 2003, that two truck trailers found in Iraq were not mobile units for manufacturing bioweapons, as had been suspected.

Two days later, President Bush still asserted the trailers were bioweapons labs, and other administration officials repeated that line for months afterward.

Barton's memoir says that well into 2004, pressure from Washington kept the U.S. public uninformed about the true nature of these alleged WMD systems.

Former senior CIA officials denied such information was stifled.

The debunking of the "mobile biolabs" claim began in classified reports long before the U.S. invasion, when German intelligence in 2001 and 2002 told U.S. officials that the story's source, an Iraqi defector code-named "Curveball," was unreliable, official investigations later found. U.N. inspectors determined in early 2003, before the war, that parts of Curveball's story were false.

In April 2003, however, two unusually equipped trailers were found in Iraq and the CIA declared they were the mobile biolabs described by the defector.

This story quickly fell apart behind the scenes, it has since emerged. Testing the equipment in early May 2003, U.S. experts found no traces of biological agents, and later that month the U.S. fact-finders filed their negative report from Baghdad.

But on May 29, Bush assured Polish television: "We found the weapons of mass destruction. We found biological laboratories." Then national security adviser Condoleezza Rice and Secretary of State Colin Powell later made similar statements. As late as January 2004, Vice President Dick Cheney called the trailers "conclusive evidence" of Iraqi WMD, one of the reasons given for invading Iraq.

The experts' findings were classified, never to be released, The Washington Post reported last month.

Meanwhile, in Australia in mid-2003, Barton writes, he viewed photos of the trailers at a CIA Web site and determined that the suspected biological "fermenter" was no such thing, and warned Australian government officials against the story.

Returning to Baghdad in late 2003 to join the CIA-commissioned Iraq Survey Group in a senior role, Barton found that specialists had dismissed the "biotrailer" suspicions. Strong evidence showed the units were instead designed to make hydrogen for weather balloons, as Iraqis claimed.

David Kay, then chief inspector, has since said that in December 2003 George J. Tenet, then CIA director, wouldn't accept this finding.

That February, Tenet claimed in a Washington speech that the trailers could be used to make bioweapons.

Barton says he, too, ran into roadblocks in early 2004 when he sought to include the trailer analysis in a report.

Barton quotes the American head of the biological team, whom Barton doesn't name, as telling him, "You don't understand how difficult it is to say anything different" from the public CIA line.

In the second half of February 2004, the book says, the newly arrived senior CIA officer in the Iraq Survey Group _ also unidentified _ told Barton he couldn't mention the trailers in a report scheduled for March.

"I don't care that they are not biological trailers. It's politically not possible," Barton recalls him saying.

The Australian says he wrote in his diary afterward, "The only reason we are going down this route is the politics in Washington."

When the Iraq Survey Group's progress report was filed in March 2004, and new chief inspector Duelfer testified to Congress, the trailers were not mentioned.

For this and other reasons, "remaining in the ISG was to be complicit in deceit," Barton writes. He and other British and Australian experts quit the inspectors group during this period.

Asked for comment on Barton's account, Duelfer said he decided not to report issues piecemeal, but in a final comprehensive report.

"I did not think those were mobile biological weapons labs," he said, but "I wanted to understand the issue of mobile BW production, whether it (the trailers) was part of a larger thing or not." He said he was not pressured by Washington.

Tenet declined to comment. But former CIA spokesman and Tenet associate Bill Harlow told The Associated Press, "There was no effort to stifle any reporting from the field by David Kay or anyone else."

Ultimately the truth about the trailers was disclosed in the Iraq Survey Group's final report in October 2004, more than 16 months after the first conclusive findings were made.