The F.B.I. is refusing to provide Congress with data it is seeking on an F.B.I. informant who provided information about two of the September 11 hijackers.

"The Federal Bureau of Investigation had a confidential informer who rented rooms in California to two of the Sept. 11 hijackers, but the bureau is resisting a request from the Congressional committee investigating the attacks to interview the informer and his F.B.I. handler, government officials said."

"The joint Sept. 11 Congressional committee plans to hold a closed hearing on Wednesday focusing on the F.B.I.'s handling of its San Diego informer, who was the landlord of the hijackers Khalid al-Midhar and Nawaq Alhazmi a year before the attacks."

"Several officials said the F.B.I. had rebuffed requests to make the informer available to the committee and would not authorize the agent who was his contact to testify."

"The F.B.I.'s resistance has led Congressional officials to become more aggressive in trying to find out whether the informer provided clues about the hijackers that the bureau ignored or failed to act on before Sept. 11."

Congress has a specific interest in these two hijackers who were aboard the American Airlines flight that crashed into the Pentagon: The CIA had identified them as Al Qaeda operatives back in January, 2001.

The CIA did not ask for them to be placed on a watch list until August--and by then the two were already in the country. Nor did the CIA pass the information on the two to the F.B.I. until late August. Some members of Congress speculate that these two hijackers were key to the whole 9/11 plot and had they been caught, the attacks may have been foiled.