LONDON – A British Airways flight from London to New York was forced to turn back yesterday after American authorities refused to allow one of the passengers to land, saying he posed a terrorist threat, the airline said.

Flight BA175 was three hours into its journey to John F. Kennedy International Airport when it was forced to turn back to London’s Heathrow Airport, where the passenger was met by police.

U.S. Transportation Security Administration spokeswoman Yolanda Clark said the passenger was traveling on a French passport.

The TSA said the man was a positive match with an anti-terrorism watch list.

London’s Metropolitan Police said they were questioning the man but had not arrested him. The TSA determined that British Airways followed proper procedures in checking the man’s name against the no-fly list. It was only after the plane took off that the airline sent the passenger manifest to U.S. Customs and Border Protection, which matched the name against the list.

“The flight returned to Heathrow after we received a request from the U.S. authorities saying that a passenger aboard the aircraft was not to be allowed to land in New York,” an airline spokesman said. “We stress that there was no threat to the safety of the aircraft.” Passengers were rescreened, and the plane took off again for New York, British Airways spokesman Honor Verrier said.

It is standard procedure for international flights leaving for America to send their passenger manifests after the plane takes off, but the American government wants to change that practice so the manifests are sent beforehand.

A federal official, speaking on condition of anonymity, said it appears the passenger was not initially discovered because the airline did not have the latest version of the no-fly list. The distribution system changed recently and the passenger was added to the list in late December, the official said.