With U.S. authorities taking an increasingly aggressive security stance on international flights headed for the United States, a British Airways jet was isolated shortly after it landed at Washington Dulles International Airport and some of its 247 passengers questioned.
Homeland Security spokeswoman Rachel Sunbarger said intelligence led the agencies to detain the flight Wednesday night, but an FBI official, speaking on condition of anonymity, told The Associated Press the incident did not involve terrorism.
On Thursday, the airline canceled the same flight, BA 223, outright following security advice from the government, a British Airways (search) spokesman said.
A Department of Transport spokeswoman said she was unable to comment on matters of security or whether the cancellation was a result of a specific threat.
The spokesman said alternative arrangements had been made for the 180 passengers on Thursday's flight, which had been scheduled to leave London's Heathrow airport (search) at 10:05 a.m.
Transportation Security Administration (search) spokeswoman Jennifer Marty said passengers aboard Wednesday's flight were questioned aboard the plane, which landed at 7:06 p.m. EST. Officials began allowing passengers off the plane around 10:30 p.m.
Sunbarger said the baggage on board the flight underwent additional screening.
The plane was kept several hundred feet from the terminal during the questioning.
Passenger David Litwick told WJLA-TV in Washington that he and his wife were not questioned, but at least one other passenger was.
Litwick said four FBI agents spoke to a woman who appeared to be from the Middle East, repeatedly asking her why she was not traveling with her husband.
Earlier this week, a scheduled U.S.-bound flight from Mexico was canceled because of security concerns.
"The government of Mexico made the decision to cancel Aeromexico Flight 490 after the U.S. government shared threat information with the Mexican government," Department of Homeland Security spokesman Brian Roehrkasse said.
Previous reports said the plane turned around in midair, but Roehrkasse and Mexican officials said it never took off. Roehrkasse denied that the U.S. government told Mexico it would refuse the plane landing rights.
However Agustin Gutierrez, Mexico's presidential spokesman, said the flight was canceled after United States authorities said they would refuse to allow it to land. He also said Mexico did not receive convincing information for the cancellation.
"The question is what threat?" Gutierrez said. "This question must be answered by Homeland Security. If we are going to have a good climate of cooperation, the least that we can hope for are reasons."
Mexican officials found no evidence of a threat on the flight, Gutierrez said.
The New York Times reported Wednesday that there have been five or six recent instances of security officials meeting planes and doing "reverse screenings" such as the one in Dulles, interviewing passengers and searching them for explosives, weapons and other contraband.
It also said there was an instance several days ago in which a flight headed for the United States from an unidentified Latin American country was grounded on the runway for several hours before being allowed to take off after United States officials told the air carrier they were not satisfied that passengers had been adequately screened initially.
The New York Times also reported that the United States had reached an agreement with a French delegation under which the French would turn over passenger lists for any at-risk flight at least one hour before takeoff, rather than waiting until the flight is in the air, as is now done.
Several Air France flights between Paris and Los Angeles were canceled Dec. 24 because of terrorism concerns.