NEW YORK (REUTERS) — A U.S.-based cell of Osama bin Laden’s al Qaeda network nearly launched a post-Sept. 11 attack on a major target in Washington before going underground or fleeing the country, Newsweek reported Sunday.

The news magazine cited intelligence sources as saying an al Qaeda “sleeper cell” in the United States was poised to launch the attack — perhaps against the U.S. Capitol. Bin Laden and al Qaeda are blamed for the Sept. 11 attacks on the World Trade Center and Pentagon that killed nearly 3,900 people.

In its Dec. 17 edition, Newsweek said the intelligence sources believed the FBI in its sweep against visa violators and other suspects of Middle Eastern backgrounds picked up members of a “support cell” assigned to provide logistics help to the people actually carrying out the mission.

The would-be attackers then went underground or fled the country, the sources said. Investigators had not been able to identify the plotters from among the hundreds of people detained by the FBI and were not even sure they were still in custody, Newsweek reported.

The U.S. government has issued three alerts warning of possible, unspecified attacks and putting Americans on a state of high alert since the Sept. 11 attacks.
U.S. Attorney General John Ashcroft has said federal criminal or immigration charges have been brought against more than 650 people since Sept. 11, including a number of ”suspected terrorists” and suspected members of al Qaeda.