A bomb threat against a Virgin Airlines jet carrying 314 people caused four Canadian jet fighters to escort it to an unscheduled landing in Newfoundland.
Capt John Pulchny of the Canadian Department of National Defence said the four F-18s were sent up by the North American Aerospace Defence Command under a heightened state of security after last week's terrorist attacks.
The Boeing 747 flying from Heathrow Airport to New York's JFK International Airport was diverted to a airport in Goose Bay in northern Newfoundland.
A Royal Canadian Mounted Police spokeswoman said the airline notified Canadian authorities of the threat and the aircraft landed safely.
She refused to provide details of the bomb threat but said it was external instead of from someone on the flight.
Capt Pulchny said Canada's transport ministry notified the Goose Bay airport about the situation. "We did not know what the emergency was on board," he said.
He called the reaction by the jet fighters part of the "added security posture" since terrorists hijacked four US aircraft and crashed three of them into the World Trade Center and the Pentagon.