Larry Di Rita said that some research into the matter continues, but thus far there has been no evidence that the intelligence unit, called "Able Danger," came up with information as specific as an officer associated with the program has asserted.
"What we found are mostly general references to terrorist cells," Di Rita said, without providing detail.
That officer, Army Reserve Lt. Col. Anthony Shaffer, Atta and three other future Sept. 11 hijackers in 2000. But, he said, military lawyers stopped the unit from sharing the information with the FBI out of concerns about the legality of gathering and sharing information on people in the United States.
"We recognized there are linkages and patterns of linkages to the al Qaeda leadership,"
His assertions have been publicized by Rep. Curt Weldon, R-Pa., vice chairman of the House Armed Services and Homeland Security committees.
Di Rita said Pentagon researchers have found no evidence that Able Danger had Mohamed Atta's name. He said he was unsure whether the unit came up with the identities of the other three hijackers but then said that none of Shaffer's specific claims had been validated.
Shaffer himself has not provided any documentary proof, Di Rita said, and said Shaffer has presented his information as second hand.
Shaffer's lawyer, Mark Zaid, said last week that Shaffer does not have documentation related to Able Danger because his security clearance was suspended in March 2004 for "petty and frivolous" reasons. They include a dispute over mileage reimbursement and charges for personal calls on a work cell phone, Zaid said.
Shaffer also has said the Sept. 11 commission failed to investigate his assertions after he spoke to members of the panel in 2003. A statement Aug. 12 by former commission chairman Thomas Kean and vice chairman Lee Hamilton said the commission did not obtain enough information on the operation to consider it historically significant.
Over the weekend, the Washington Post reported that the CIA has completed and turned in its report on the Sept. 11 terrorist attacks and turned it over to CIA director Porter Goss in June for review. The Post learned that Goss received the report in July and is still ruminating over how to respond to its findings.
The report, by Inspector General John L. Helgerson, is expected to be sent to congressional intelligence committees after Goss finishes his review.