Ijaz reported back to the National Security Council and members of Congress.
"It was an offer U.S. officials did not take seriously," Carney said.
"There was no willingness to engage with Sudan to build a minimal level of trust that might — and I use the word 'might' very strongly here — might have elicited those kinds of documents that Mr. Ijaz subsequently saw," Carney said.
A congressional panel will now investigate the Sudanese offer, ABCNEWS been told.
"Why wouldn't we be accepting intelligence from the Sudanese?" said Sen. Bob Graham, D-Fla., who is the co-chairman of the bicameral congressional hearings into the intelligence community's failure to foresee the Sept. 11 attacks. "Was there some reason to believe that they were engaged in disinformation?"
Susan Rice, who was responsible for U.S. policy on Africa under the Clinton administration, said the reason is that after many meetings with the Sudanese, there was no real offer of intelligence files.
"We wanted names. We wanted bank accounts. We wanted paper. We wanted the bodies themselves, the individuals to interview," she said. "And none of that was forthcoming."
Instead of cooperating with Sudan, the United States struck a Sudanese pharmaceutical factory in retaliation for the 1998 bombings of U.S. embassies in Kenya and Tanzania. U.S. officials have blamed bin Laden for planning and funding these bombings.
Clinton administration officials insisted the plant was involved in chemical weapons production, a claim that was disputed strongly by the plant's owner, who has since sued the U.S. government.
The Defense Intelligence Agency later raised doubts about the target, stating in a review that the strike was based on "bad science and bad intelligence."
Clinton Not Willing to Risk Lives
After the embassy bombings in Africa, President Clinton signed a series of orders authorizing the use of lethal force to capture or kill bin Laden.
According to intelligence sources, the United States had information on bin Laden's location on three occasions since 1998. But the Clinton administration was not willing to risk losing American lives.
"We were risk-averse as a nation," said Michael Sheehan, the coordinator for counterterrorism at the State Department from 1998 to 2001. "And going after terrorism prior to 9/11, the military was also clearly risk-averse."
Former Sen. Bob Kerrey of Nebraska, a Democrat who is a former special forces soldier, said the lesson officials should have learned was that "if you don't respond militarily, you're going to get attacked again."
"Can you imagine you're out on the front lines of a combat operation and somebody mortars you one night and the next thing you know you've got lawyers coming around saying they're going to go out and investigate it and try to find out whether they can bring a criminal charge to find out who did it?" asked Kerrey.
In another sign of a missed opportunity, the United States received intelligence a month before Sept. 11 that bin Laden's right-hand man, Ayman Al-Zawahiri, was receiving medical treatment at a clinic in San'a, Yemen, ABCNEWS has learned.
The Bush administration rejected a plan to capture him as officials could not be 100 percent sure the patient was Al-Zawahiri, sources said.
Many officials now believe that opportunities were missed because they underestimated the threat.
"I did not see it with the force that I now see it, or with the priority that it now has," said John Gannon, a former deputy director at the CIA and former chairman of the National Intelligence Council. "So it was not that I missed an opportunity, it was that I, as an analyst — I thought, a pretty hard-working analyst — I was wrong."
The government's fight against terrorism always seemed to fall short, reflecting competing interests and competing judgments.
"It was not just the intelligence agencies, actually; they were at least working on the problem," said Woolsey, the former CIA chief. "The whole country was in a mode of thinking, 'It can't happen here, and anyway, I don't want to be bothered.'"