American intelligence agencies believe terrorists were planning a Christmas attack more devastating than the September 11th atrocities, the Bush administration claimed last night.
The US administration disclosed it stepped up security after "a stream of intelligence" pointed to an air attack on American cities.
Homeland Security Secretary Mr Tom Ridge said: "It talks about attacks equal to or greater than those that occurred on September 11th, talked about these attacks occurring in a time frame that covered our traditional holiday period, and it also included reference to aviation."
Mr Ridge told BBC2's Newsnightprogramme the intelligence pointed to specific flights which the British, French and Mexican governments "are very much aware of".
Mr Ridge was speaking after talks with British government officials in Washington over improving airline security. He said both countries wanted to draw up guidelines on how to respond to terror threats.
The talks came as British Airways flight BA223 from Heathrow to Washington, DC, finally took off tonight after being delayed for the fifth successive day over terrorism fears.
PA