Washington ? The 9-11 commission will investigate a claim that U.S. defense intelligence officials identified ringleader Mohammed Atta and three other hijackers as a likely part of an al-Qaida cell more than a year before the hijackings but didn’t forward the information to law enforcement.

Rep. Curt Weldon, R-Pa. and vice chairman of the House Armed Services and Homeland Security committees, said Tuesday the men were identified in 1999 by a classified military intelligence unit known as “Able Danger.” If true, that’s an earlier link to al-Qaida than disclosed intelligence about Atta.

Sept. 11 commission co-chairman Lee Hamilton said Tuesday that Weldon’s information, which the congressman said came from multiple intelligence sources, warrants a review. He said he hoped the panel could issue a statement on its findings by the end of the week.

“The 9/11 commission did not learn of any U.S. government knowledge prior to 9/11 of surveillance of Mohammed Atta or of his cell,” said Hamilton, a former Democratic congressman from Indiana. “Had we learned of it obviously it would’ve been a major focus of our investigation.”

The 9-11 commission’s final report, issued last year, recounted numerous government mistakes that allowed the hijackers to succeed. Among them was a failure to share intelligence within and among agencies.

According to Weldon, Able Danger identified Atta, Marwan al-Shehhi, Khalid al-Mihdar and Nawaf al-Hazmi as members of a cell the unit code-named “Brooklyn” because of some loose connections to New York City.

Weldon said that in September 2000 Able Danger recommended that its information on the hijackers be given to the FBI “so they could bring that cell in and take out the terrorists.” However, Weldon said Pentagon lawyers rejected the recommendation because they said Atta and the others were in the country legally so information on them could not be shared with law enforcement.