At the same time, a senior intelligence official says the CIA shared with other U.S. agencies its doubts about prewar reports — later proven false — that Iraq sought uranium from Niger.
Despite these doubts, the CIA passed the information along anyway, and the reports made it into President Bush's State of the Union address.
About a month after Bush's January 2002 speech, the United Nations determined the uranium reports were based primarily on forged documents initially obtained by European intelligence agencies.
In an interview Thursday with The Associated Press, Powell said the Bush administration believes Saddam Hussein had both deadly weapons and programs to develop them. He suggested that the United States would help Iraqi scientists if they share what they know about Saddam's weapons.
"Saddam Hussein kept them together so that if the opportunity ever presented itself, he could create nuclear programs. We want to make sure those scientists are no longer kept together in a cell ... but that they go on to find other things to do," Powell said.
When U.S. and British teams finish their searches of suspected weapons hiding places, their interviews with knowledgeable Iraqis and their exhaustive review of documents, "it will lead us not only, we believe, to weapons that may exist, but to the programs themselves," Powell said.
"We believe there were weapons in Iraq. We have solid judgment of the intelligence community on this," Powell said.
Iraqi exile leader Ahmed Chalabi said Thursday his group had introduced U.S. officials to three defectors who provided information on Saddam Hussein's banned weapons.
Chalabi, head of the Iraqi National Congress, told reporters that he believed the United States would find the weapons and the toppled Iraqi president — if it worked more closely with Iraqi groups that had opposed Saddam's government.
The weapons Saddam was accused of making and hiding have not turned up, despite weeks of searching since the war in Iraq ended. That has prompted questions about the accuracy of the intelligence the United States used to glean information about Iraq's arsenal.
Leading Senate Democrats want an investigation into the question of whether intelligence on weapons programs was inaccurate or manipulated to make the case for war.
Senate Intelligence Committee chairman Pat Roberts said questions about U.S. intelligence will instead be examined in closed door hearings beginning next week.
"We're going to complete a very thorough review of all the documentation," said Roberts, a Kansas Republican.
The chairman of the House Intelligence Committee, Rep. Porter Goss, R-Fla., and the panel's top Democrat, Rep. Jane Harman of California, said they would begin closed hearings next week as part of their review. On Wednesday the committee will hear about current efforts to locate weapons of mass destruction; on Thursday it will hear testimony about an October 2002 intelligence review of Iraq's weapons programs.
In a statement outlining their plans, they said future hearings will allow committee members to question senior administration officials about the weapons intelligence. Hearings will be open "as appropriate." The review will include a final written report, with an unclassified summary.
Two trailers have been found that U.S. officials said were part of mobile biological weapons labs, although that hasn't been proven conclusively. In the AP interview, Powell said the Bush administration would be able to "demonstrate convincingly" that the trailers were labs in which biological weapons could be made.
That aside, the United States has not been alone in alleging Iraq had weapons, Powell said. "As late as 1998, there never was a question in anybody's mind. Other intelligence organizations in other countries said so," he said.
"This isn't a figment of somebody's imagination. This isn't something that was overblown, or made up in the basement of the CIA late one night," Powell said. "These were real weapons, real programs, that Saddam Hussein refused to come forward and explain. ... Do you want to give Saddam Hussein the benefit of the doubt? Well, we didn't. And now we don't have to worry about it anymore."
A Bush administration official said the Niger nuclear information was vetted by relevant agencies, and it was included in the president's speech because at the time it was believed to be reliable. It is no longer regarded as such.
The Washington Post, quoting unidentified U.S. officials, reported Thursday that the CIA did not pass on the detailed results of its investigation to the White House or other government agencies.
The U.S. intelligence official, however, said the CIA's doubts were made known to other federal agencies through various internal communications, starting more than a year before the war began.
Questions have been raised about whether agencies relied too much on exile groups for information about weapons programs.
Chalabi, who spoke after meeting with a group of about 30 lawmakers, said "there was no hyping of information."
"There was no information that was given that was not substantiated," he said. "And the record will speak for itself."
Chalabi said he told lawmakers about three defectors who had provided the U.S. government with information on Iraqi weapons programs.
One was an engineer "who built sites for the weapons storage areas." He was presented to the U.S. government on Dec. 17, 2001, and entered into the witness protection program, Chalabi said.
The second exile told the United States about mobile biological labs, he said. U.S. officials believe two truck trailers it seized in Iraq were likely those labs. But no traces of biological weapons have been found.
The third exile spoke only briefly to U.S. officials. Chalabi said he was involved in the isotope separation program for nuclear weapons.
Chalabi is a former banker who recently returned to Iraq after 45 years abroad. Supporters credit him with keeping U.S attention on Iraq in the past decade and some U.S. officials see him as a potential future leader of Iraq.
But it is unclear how much support he has in Iraq, after spending most of his life in exile. Critics have also questioned his credibility, noting that a Jordanian court convicted him in absentia of embezzlement in 1992.