US warplanes have been tailing in-bound Air France flights amid fears they may be crashed by hijackers into United States targets, it has emerged.
With air security at a state of heightened alert over the holiday period, some British and Mexican flights to the US were also cancelled, while oil shipments from Alaska's major port of Valdez were suspended for two days.
The halt of transfers of oil onto tankers began on Tuesday but was lifted yesterday. Valdez is the terminal for the 800-mile trans-Alaskan pipeline which normally carries about 1 million barrels a day or about 17 per cent of US domestic production.
An Aeromexico flight to Los Angeles from Mexico City was canceled on New Year's Eve and January 1st and British Airways canceled both legs of one of its three daily flights from London to Washington on security advice from the government.
A Bush administration official said US intelligence remained particularly concerned about "credible" threats to Los Angeles-bound flights from Paris and Mexico City.
The day before, passengers aboard the same inbound flight, BA 223, were held on the tarmac at Washington's Dulles International Airport for several hours of questioning but no arrests were made.
Six flights between Paris and Los Angeles were canceled on December 24th and 25th after US officials spotted what they believed were suspicious names on lists of those due to board the planes.
Combat aircraft such as F-16s stepped up patrols and escorted a number of Air France flights, officials confirmed.
When this happens in the middle of the day and there are two F-16s outside of an aircraft, you obviously don't keep it a secret," said one official.