Security and airline officials said the flights on Sunday and Monday were cancelled after fears that al-Qaida was seeking to repeat the September 11, 2001 attacks in which planes were hijacked and crashed in New York City and Washington.

"There was specific credible threat information that was shared with some foreign governments, including the British and French governments and the decisions were made to cancel these flights," said an unnamed US Homeland Security Department source.

The official said there were no plans to raise the nation's threat level, which has been "elevated" since 9 January.

The Washington Post newspaper, citing unnamed senior administration officials, also reported on Sunday that the cancellations were sparked in part by intelligence indicating that al-Qaida was seeking to release chemical or biological agents on board an airliner.

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Air France cancelled Paris to Washington flights on Sunday and Monday, just hours after British Airways cancelled its London to Washington flights on Sunday and Monday. British Airways also cancelled a London to Miami flight on Monday.

Air France also scrubbed two Washington to Paris flights, both the return trips for the cancelled Paris to Washington flights.

Likewise, British Airways annulled two flights from Washington to London on Sunday and Monday.

In addition, Continental airlines cancelled a flight from Glasgow, Scotland to Los Angeles via New York.

The carrier said on its website the flights were cancelled for "security reasons".

Washington, London and Paris were on heightened alert throughout the Christmas and New Year high travel season for fear of another September 11-style attack.