Lawrence Wilkerson, a former U.S. Army colonel who retired last year, said he learned after the secretary of state's February 2003 speech that key elements were wrong, based on faulty or manipulated intelligence.

Sen. Dianne Feinstein, a California Democrat who has served six years on the Intelligence Committee, said Powell's speech was "a singular event, because no one was more respected.''

"Putting that man before the world with information that was not correct was a dastardly thing to do,'' she added.

Feinstein was one of three senators who presided over a hearing by the Democratic Policy Committee on the use and misuse of pre-war intelligence on Iraq.

Democratic and Republican policy committees, set up by the Senate 60 years ago, occasionally hold forums that don't have the legislative weight of a congressional committee hearing, but can spotlight an issue not receiving attention elsewhere.

Senate Republicans belittled the hearing as partisan theater, while Democrats pointed out that with the GOP controlling Congress, no committee hearings have been held on pre-war intelligence.

Four former government officials, with a combined experience of more than 100 years, participated in the hearing. Two of them, Wilkerson and former Assistant Secretary of State Carl Ford, said they were Republicans.

Paul Pillar, a CIA official who coordinated U.S. intelligence on Iraq, said he believes that that decision to invade Iraq was made by summer 2002, "and instead of intelligence informing a policy decision, it was used to justify a decision already made.''

Feinstein has pushed for an investigation of the role played by Iraqi exiles, especially the Iraqi National Congress, and a special Pentagon intelligence office in pushing the country into war.

"There is still much that we don't know about how this happened,'' she said.

The hearing also touched on how top officials were blindsided by the Iraqi insurgency in 2003. Wayne White, the State Department's principal Iraq analyst, said the military did not listen to his warning that there was 'a vast and renewable pool'' of militant Iraqis willing to attack U.S. forces.