But the spokesman said the Pentagon remains uncertain what level of detail was provided to the official commission that investigated the attacks on the World Trade Center in New York and the Pentagon.
"We are looking into what information - and in what detail - was provided to the commission, but as I understand it, at least some of this information was provided," said Bryan Whitman, a Pentagon spokesman.
"We are looking to better understand what information was developed and then what information was also provided to (the commission)," he said.
Asked whether there was knowledge of Mohammed Atta, the reputed leader of the September 11 hijackers, before the attacks, Whitman said: "We're looking further into it."
Representative Curt Weldon, a Republican, has said that a military intelligence operation called Able Danger identified Atta and three other future hijackers in mid-2000 as members of a US-based al-Qaida cell.
It was the first report that Atta had been identified by any US intelligence agency before September 11.
A former military intelligence official made available to reporters through Weldon said the information, including the hijackers' names and pictures, was presented to the US Special Operations Command in Tampa, Florida, in 2000.
The official told The New York Times that Able Danger members had recommended that the information be shared with the FBI, but the recommendation was rejected.
Marwan al-Shehhi (L) was identified
with Mohammed Atta
The official also said he was among a group who briefed the executive director of the commission, Philip Zelikow, and three other commission staffers about it in October 2003 during a visit they made to the Afghanistan-Pakistan region, according to the Times.
He said he explicitly mentioned Atta as a member of the US-based cell. The commission chairman, Thomas Keane, told the Times no staffer remembers any mention of Atta.
The commission's report, which was released last year, made no mention of the Able Danger, an operation that reportedly used data-mining techniques to identify al-Qaida suspects.
The commission criticised the intelligence gathering operation of the FBI and CIA before the attacks because of signs that an attack was being planned.
Lee Hamilton, the commission's former vice chairman, said panel staff interviewed Able Danger members in Afghanistan in October 2003 and later reviewed documents on the operation supplied on request by the Bush administration.
"Neither in the documents nor in the conversations was there any mention of a Mohammed Atta or his cell," Hamilton, a former Democratic congressman from Indiana, told Reuters in an interview. "There was no mention of Mohammed Atta and no mention of any military surveillance of him."
The Pentagon says it is looking
into the information
The former military intelligence official insists he personally told September 11 commission staff members about Atta in Afghanistan, and offered to supply them with documents upon his return to the United States, only to be rebuffed.
Former September 11 commission spokesman Al Felzenberg said on Tuesday that the panel's former staff would review internal memos and other documents to make sure information about Atta was not overlooked.
"We will know by the end of the week whether we missed something," Felzenberg said.
Defense Secretary Donald Rumsfeld said he was unaware of the intelligence information. Able Danger, now disbanded, was a small classified military operation engaged in data-mining analysis of "open source" information including media reports and public records through the use of powerful computer systems.
"We don't know whether the lawyers were with the DOD or the White House. All we know is that (the Able Danger members) were stopped"
US legislator from Pennsylvania
Weldon, a Pennsylvania Republican who is vice chairman of the House Armed Services and Homeland Security committees, said the information was provided to the staff of the September 11 commission but some commissioners were never briefed on the material.
Weldon and the former military official, who spoke to Reporters in the congressman's office, are encouraging intelligence officials to consider a resumption of the activity, which could mean as much as $30 million in new business for defense and intelligence contractors.
The former military official said his unit recommended that information identifying Atta and fellow hijackers Marwan al-Shehhi, Khalid al-Mihdhar and Nawaf al-Hazmi as part of an al-Qaida cell they called "Brooklyn" be forwarded to the FBI.
"They were in the country at least a year before 9/11," said the former military intelligence official, who asked not to be identified because of the sensitivity of the information.
But government lawyers advised the military's Special Operations Command, which oversaw Able Danger, not to forward the information apparently because the four were in the United States legally on visas and should not be subject to a military operation.
"We don't know whether the lawyers were with the DOD or the White House. All we know is that (the Able Danger members) were stopped," said Weldon.
Weldon said he may ask for a formal inquiry into the issue after Congress returns from its August recess.