An American Airlines jet bound for Dallas returned to Houston Intercontinental Airport shortly after takeoff yesterday after passengers thought they spotted a person with a weapon on board, an airport spokesman said.

Flight 1702, flying on the anniversary of the September 11 attacks, was escorted to the airport by two F-16s and two suspects were taken into custody, but investigators have found no weapons on the plane, spokesman Ernie DeSoto told reporters.

An FBI spokesman initially said it appeared to be a possible hijacking, but a US Transportation Department official, who spoke on the condition of anonymity, said the government does not believe it was. The official did not elaborate.

Television reports showed the Fokker 100 jet with 50 passengers on board taxiing to the terminal surrounded by Houston Police Department cars.

"There were never any threats made or anything but the pilot decided it would be better to be safe than take a chance so he came back" after a passenger reported spotting a possible weapon, DeSoto said.

The flight was escorted by two F-16 back to Intercontinental and kept in a secure area," he said. "At this point in time there have been no weapons found whatsoever."

American Airlines spokesman Gus Whitcomb told Reuters there were two US air marshals on the flight.

Two American Airlines jets were used by hijackers in the September11 attacks.