Mr. Tenet issued a statement last night after both the president and his national security adviser placed blame on the C.I.A., which they said had reviewed the now discredited accusation and had approved its inclusion in the speech. 

For days, the White House has tried to quiet a political storm over the discredited intelligence, which was among many examples cited in Mr. Bush's speech to justify the need for confronting Iraq to force the dismantlement of Saddam Hussein's arms programs.

"I gave a speech to the nation that was cleared by the intelligence services," the president said after a meeting in Uganda with President Yoweri K. Museveni, for the first time placing implicit blame for his error on those agencies. 

Condoleezza Rice, the president's national security adviser, speaking to reporters on Air Force One en route to Uganda, said, "The C.I.A. cleared the speech in its entirety."

Although Mr. Tenet's statement did not say he had personally cleared the speech, he said in his statement, "I am responsible for the approval process in my agency."

In an administration that prides itself on discipline and message control, the question of how faulty intelligence got into Mr. Bush's speech has become an unusual exercise in finger-pointing, with top officials and agencies blaming one another. 

In his State of the Union address, Mr. Bush cited an Iraqi attempt to purchase uranium from Africa as part of evidence of Mr. Hussein's unconventional weapons and Iraq's desire to reconstitute its nuclear program.

"The British government," the president said, "has learned that Saddam Hussein recently sought significant quantities of uranium from Africa."

Mr. Tenet said yesterday: "The president had every reason to believe that the text presented to him was sound. These 16 words should never have been included in the text written for the president."

Other senior administration officials had been more cautious about the information. In a recent interview, Secretary of State Colin L. Powell said that by the time he got to a meeting that Mr. Tenet attended at the C.I.A. three nights after the president's Jan. 28 speech, Mr. Powell's staff had already dismissed any thought of using the Africa claim to bolster the case the secretary was to make a few days later at the United Nations.

The intelligence agencies, Mr. Powell said, were "at that point not carrying it as a credible item."

In a briefing with reporters on Thursday night in South Africa, Mr. Powell suggested that he had looked into the assertion more closely and decided it was not based on sufficiently reliable information to repeat to the United Nations.

"When I made my presentation to the United Nations and we really went through every single thing we knew about all of the various issues with respect to weapons of mass destruction, we did not believe that it was appropriate to use that example anymore," he said. "It was not standing the test of time. And so I didn't use it, and we haven't used it since."

Yesterday, Ms. Rice said Mr. Powell's decision had not been driven by any new information but by longstanding concerns in the State Department's own intelligence branch about whether the data was reliable.

The State Department's intelligence unit, Ms. Rice said, "was the one that within the overall intelligence assessment had objected to that sentence." 

In the classified version of a National Intelligence Estimate prepared by intelligence agencies last fall, the allegation about Iraq's activities in the African nation of Niger was included along with a footnote that said the State Department had its doubts about whether it was justified by the evidence. Somalia and Congo were also cited in the estimate.

Ms. Rice said the administration did not learn until March that the documents that were the primary basis for the assertion about Niger had been forged. She also said she did not learn about the mission to Niger last year by a former American ambassador — who found no evidence to back up the charge — until a month ago, when she was asked about it during a television interview.

In recent days, the C.I.A.'s spokesman said Mr. Tenet had never personally approved Mr. Bush's use of the African uranium example in the speech. But Dan Bartlett, one of Mr. Bush's closest aides, who drafted parts of the address, said in an interview that the wording had been "cleared at the highest levels of the C.I.A." which would seem to mean Mr. Tenet or his deputy, John McLaughlin.

Inside the National Security Council, some senior staff members gave a slightly different account, saying the paper trail suggests the claim about Africa may have been approved at the agency's midlevels, by a senior expert on nuclear proliferation and arms control.

A senior administration official said Ms. Rice had telephoned Mr. Tenet before she spoke to reporters yesterday. Asked whether the White House continued to have confidence in Mr. Tenet, Ms. Rice replied, "Absolutely."

But Mr. Tenet was clearly an official under fire yesterday. Senator Pat Roberts of Kansas, the Republican chairman of the select committee on intelligence, said he was "disturbed by what appears to be extremely sloppy handling of the issue from the outset by the C.I.A."

He added that he was most worried about "a campaign of press leaks by the C.I.A. in an effort to discredit the president." He accused Mr. Tenet of failing to warn Mr. Bush about any doubts in the agency.

The Senate, by voice vote on Thursday night, called for an investigation into what led to Mr. Bush's statement.

There are still major questions about whether there was a failure to communicate the doubts of some intelligence analysts to the White House or whether, as some senior intelligence officials maintain, in the prelude to the war, the White House stripped much of the nuance and balance from intelligence reports to make the threat from Mr. Hussein seem more urgent and the need for action more immediate.

There is evidence that there was concern in the C.I.A. about the credibility of the uranium information and that those doubts reached at least some White House officials months before the State of the Union address. Administration officials involved in drafting another speech Mr. Bush gave about Iraq, in Cincinnati on Oct. 7, said that at the C.I.A.'s behest, they had removed any mention of the central piece of intelligence about African uranium — a report about an effort by Iraq to obtain "yellowcake," which contains uranium ore, in Niger. No one has fully explained how, given that early October warning to the White House, a version of the same charge resurfaced in the early drafts of the State of the Union address just three months later, and stayed there, draft after draft.

Ms. Rice said yesterday that the new wording Mr. Bush used in the address had been reviewed and changed by the C.I.A., whose officials initially expressed concern about some "specifics about amount and place." After the changes, she said, "the C.I.A. cleared the speech in its entirety."

"If the C.I.A., the director of central intelligence, had said, `Take this out of the speech,' it would have been gone, without question," she added. "If there were doubts about the underlying intelligence, those doubts were not communicated to the president, to the vice president or to me."

Mr. Bush, Ms. Rice and Mr. Powell all insist that the political furor over one line in Mr. Bush's speech obscures what they say is a larger truth: that Mr. Hussein was trying to reconstitute his nuclear program, and had sought to obtain key components for it around the world.

So far, investigators on the ground in Iraq have found no evidence of that rekindled effort, though a barrel full of nuclear centrifuge plans and equipment was found buried for the last 12 years in the garden of one nuclear engineer in Baghdad. This strongly suggests that Mr. Hussein's government was holding onto key designs in case they had the opportunity to restart the program.

To Mr. Bush's critics, both in Congress and in the intelligence sector, the case of the African uranium is just one example of what happened to the evidence about Iraq's weapons and links to terrorism as it moved from individual scraps of intelligence, to the murky world of classified assessments, to the boiled-down language of executive summaries, to the crisp, declarative language of a president who knew, in the words of one of his top aides, that he "needed to rally the country for war."

Caveats and cautions often fell away, senior government officials and intelligence analysts in Washington and London said in recent interviews. Even when cautionary language survived, it was often drowned out in the echo chamber of talk shows and the shorthand of newspaper headlines.

Richard J. Kerr, a former deputy director at the C.I.A. and the leader of a team of retired officials who have reviewed the prewar intelligence about Iraq, said that "certainly there is a difference between the intelligence and the public statements" of some government officials. "Intelligence is always written in a way that is not particularly useful in directly supporting policy," he said. "Everybody drops qualifiers when you want to make a point and make it sing a little bit. I would be surprised if they didn't."

"These are different kinds of products," Mr. Kerr continued. "Policy statements are meant to have a fairly clear and dramatic impact. They don't convey the subtle distinctions that an intelligence analyst would make. They don't convey the cautionary note that an analyst would provide."

Greg Thielmann, a proliferation expert who worked for the State Department's Bureau of Intelligence and Research, added this week: "This administration has had a faith-based intelligence attitude: `We know the answers, give us the intelligence to support those answers.' When you sense this kind of attitude, you quash the spirit of intellectual inquiry and integrity."

In the case of the uranium, Mr. Bush actually cited British intelligence because it had published the allegation about Africa in an unclassified report in September. "It cited a public document, which probably helped," Ms. Rice explained yesterday. "It was also Britain, which probably helped."

When the first rumors of a purchase effort in Niger surfaced, at the beginning of 2002, Vice President Dick Cheney's office asked the C.I.A. to assess the information. Apparently without the knowledge of Mr. Cheney or Mr. Tenet, the agency sent a former ambassador, Joseph C. Wilson IV, to investigate. He reported back that the government of Niger had denied the report, and that other indications were that it was bogus. 

Before the speech, the crucial conversations between the C.I.A and White House over whether to include the African reference in the State of the Union address were held between Robert G. Joseph, a nuclear proliferation expert at the National Security Council, and Alan Foley, a proliferation expert at the C.I.A., according to government officials. 

There is still a dispute over what exactly was said in their conversations. Mr. Foley was said to recall that before the speech, Mr. Joseph called him to ask about putting into the speech a reference to reports that Iraq was trying to buy hundreds of tons of yellowcake from Niger. Mr. Foley replied that the C.I.A. was not sure that the information was right. 

Mr. Joseph then came back to Mr. Foley and pointed out that the British had already included the information in a report. Mr. Foley said yes, but noted that the C.I.A. had told the British that they were not sure that the information was correct. Mr. Joseph then asked whether it was accurate that the British reported the information. Mr. Foley said yes. 

Other government officials said, however, that Mr. Joseph did not recall Mr. Foley's raising any concerns about the reliability of the information. If he had, they said, Mr. Joseph would have made sure that the reference was not included in the speech. 

The White House would not say what the C.I.A. officers had been asked, or whether the issue had been raised with Mr. Tenet, who sees the president daily and speaks often with Ms. Rice and Stephen J. Hadley, the deputy national security adviser.

The White House said it was stunned to learn, after the speech, that the Niger evidence was based on false documents, and that the sources for evidence that Iraq sought the yellowcake elsewhere in Africa were far short of reliable. "What the president says has to be bulletproof," a senior American official said. "This clearly wasn't."