Washington ? The Bush administration is haunted by the history of intelligence blunders about Saddam Hussein’s supposed weapons of mass destruction as the United States tries to document that Iran is providing lethal help to Iraqi fighters.

After weeks of preparation and revisions, U.S. officials are preparing to detail evidence supporting administration’s claims of Iran’s meddlesome and deadly activities. A briefing was scheduled today in Baghdad.

The Iran dossier, some 200 pages thick in its classified form, was revised heavily after officials decided it was not ready for release as planned last month. What is made public probably would be short, and shorter on details than the administration recently had suggested.

No one who has seen the files has suggested the evidence is thin. But senior officials – gun-shy after the drubbing the administration took for the faulty intelligence leading to the 2003 Iraq invasion – were underwhelmed by the packaging.

Officials from several intelligence agencies scrutinized the presentation to make sure it was clear and that “we don’t in any way jeopardize our sources and methods in making the presentation,” State Department spokesman Sean McCormack said Friday.

National security adviser Stephen Hadley recently said some Iran material was overstated.

The evidence on Iran is intended to give backbone to the administration’s claim that an emboldened Iran is playing a dangerous game across the Middle East: meddling in conflicts and seeding terrorism beyond its borders while rushing to acquire nuclear know-how that could produce a bomb.

Government officials familiar with the dossier’s documents and slides, who spoke on condition of anonymity because the materials still were classified, said they make a compelling case about Iranian actions in Iraq.

Among the evidence the administration planned to present are weapons that were seized over time in U.S.-led raids on caches around Iraq, said one military official. Other evidence includes documents captured when U.S.-led forces raided an Iranian office Jan. 11 in Irbil, a city in Kurdish-controlled northern Iraq about 220 miles north of Baghdad, this official said.

The dossier also details Iran’s role in providing Iraqi fighters with the “explosively formed penetrator” devices that can pierce the armor of Abrams tanks with nearly molten-hot charges. One intelligence official said the U.S. is “fairly comfortable” that it knows with some precision the origin of those Iranian-made explosives.

While traveling in Europe on Friday, Defense Secretary Robert Gates said that serial numbers and markings on explosives used in Iraq provide “pretty good” evidence that Iran is providing either weapons or technology for militants there. Gates did not how the U.S. knows that, and officials in Washington declined comment.

A senior U.S. government official said Saturday that members of Congress were shown proof in December. “I’m convinced from what I’ve seen that the Iranians are supplying and are giving assistance to the people in Iraq who are killing American soldiers,” said independent Sen. Joe Lieberman of Connecticut.