Mohammed Atta and three other men who hijacked aircraft on September 11, 2001 were identified by the US Government as possible members of an al-Qaeda cell more than a year before the attacks, it was reported today.

A highly classified military intelligence unit prepared a chart showing likely al-Qaeda cells in the summer of 2000, which showed the names and photographs of the four men, according to The New York Times.

The secret military team, known as Able Danger, recommended that the identities of the four men be shared with the FBI and other parts of the military, but the recommendation was never taken up, according to a Republican Congressman, Curt Weldon, quoted by the newspaper.

Mr Weldon's account, and the information provided by an unnamed military official to The New York Times, constitute the first claim that Atta, the lead hijacker on 9/11, had been identified as a possible terrorist before the attacks took place.

Until now, only two of the 19 hijackers, Khalid al-Mihdhar and Nawaf al-Hazmi, were known to have been identified by US government agencies as threats to American security.

The CIA tracked the men through 2000 before passing their information to the FBI in the spring of 2001.

According to Mr Weldon, who said he has tried to share this information since September 2001, when it first came to his notice, the risk posed by Atta and his cohorts never spread through America'a law enforcement agencies because of the uneasy co-operation between the FBI and the military.

Mr Weldon, a Congressman from Pennsylvania, is a vice chairman of both the House Armed Services Committee and the House Homeland Security Committee.

The 9/11 Commission, appointed to investigate the causes and intelligence failures that led to the events of September 11, did not include information gathered by Able Danger in its report, which was published last year, even though the Commission learned of its existence in 2003, according to the newspaper.

The classified military intelligence unit used sophisticated "data mining" techniques, which process huge amounts of data to find patterns, to identify Atta and the three other men as likely members of an al-Qaeda cell within two months of their arrival in America in 2000.

According to the article, The New York Times was shown a chart similar to the one drawn up by the military team in the summer of 2000.

The "floor-sized chart" showed the names and photographs of Atta and Marwan al-Shehhi, as well as al-Mihdhar and al-Hazmi, as making up an US-based al-Qaeda cell known as the "Brooklyn cell".

According to the anonymous military intelligence source quoted by the newspaper, when the chart was completed it was delivered to the Special Operations Command of the US military, under whose authority the secret team worked.

"We knew these were the bad guys, and we wanted to do something about them," the official told the newspaper.

A spokesman for the US Special Operations Command told The New York Times, that no one at the command now had "any knowledge of the Able Danger program, its mission or its findings".

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