Passenger hunted over flight scare is linked to al-Qa'ida

Security alert heightens as officials confirm that suspected terrorist who failed to catch Air France flight is still at large

Anti-terrorist police are hunting a man with suspected links to al-Qa'ida who failed to turn up for a recent Paris-Los Angeles flight, triggering the deep American fears which have disrupted transatlantic travel in recent days.

French officials said they were looking for a man called Abdoulaye, who failed to turn up for the Air France flight on Christmas Eve. US intelligence believes he may be called Abdou Hai, an Afghan al-Qa'ida suspect.

The ABC television network reported earlier this week that US officials fear the man may be travelling with a miniature bomb, capable of evading airport detection systems. The network also said French police searching for the man had raided on houses in Lyons and north of Paris, acting on US information. The CNN network claimed US officials believe the missing passenger may be a trained pilot.

French officials would not confirm reports about the bomb or reveal any information about yesterday's police raids. Asked about the ABC report, the French Justice Minister, Dominique Perben, said: "I can tell you that we are looking for someone, but nothing more at this stage." The French authorities have informed their British counterparts about the continuing search for the passenger.

Three Air France flights to Los Angeles on Christmas Eve and Christmas Day were cancelled after the US warned France that it had spotted several suspect names on passenger lists. Previously, both French and American officials have said the warning was a false alarm and that all the passengers had been checked out and proved harmless.

It now appears this may have been a cover story to distract attention from the continuing search for one of the passengers who failed to turn up for the first flight on 24 December, Air France flight 68, and has not been traced since.

A Bush administration official who briefed reporters, said: "There were several passengers on that flight that were of concern and we're working with our international partners to make sure that all passengers on that flight are questioned. Two passengers did not show up. One was cleared, one remains at large."

French officials said the passenger in question had given his name as "Monsieur Abdoulaye" when he was booking his ticket. US anti-terrorism agents fear he may be Abdou Hai, an Afghan suspected of having attended al-Qa'ida training camps.

The ABC report said the fact that this one suspect was still at large was "one of the factors contributing to the continuing security jitters about transatlantic flights".

Since 21 December when the US raised the level of its security alert to high - code orange - Washington has demanded the cancellation of a number of flights from Britain to the US. Others have been delayed for lengthy periods while passenger lists were scrutinised by US security agencies.

Washington has asked for armed security guards - sky marshals - to be deployed on flights to America and it has started a controversial programme of fingerprinting and photographing many foreigners arriving in the US.

"What's important when someone doesn't take a plane is to know why he didn't take it," M. Perben, told a radio interviewer in France yesterday.

French sources said they did not know whether the man was travelling on a French passport, as ABC reported. They said there was no proof that "M. Abdoulaye" was the suspected Afghan terrorist with a similar name. But the fact that the man had proved untraceable was a legitimate concern.

There appeared to be some annoyance in both the US and France that news of the search for the missing passenger from flight 68 had leaked out. The CIA had denied the ABC report before it was confirmed, in part, by the French Justice Minister. The Interior Minister, Nicolas Sarkozy, implicitly criticised his colleague later, saying it was "too early to say anything at all on this case ... I prefer to talk only when all the facts have been checked".

On Tuesday US fighter jets escorted a passenger plane travelling from Paris to Cincinnati after a security alert involving a woman's coat. The woman was denied boarding because wires and a battery were found in her jacket. It was later confirmed that it was a "heated jacket" and that she posed no threat. Despite this, US officials ordered that the plane be escorted through US airspace.

The plan to place armed guards on flights into the US has met resistance from some countries who believe flights should be cancelled if it is deemed there is a security threat that requires a marshal. Ireland, which holds the EU presidency, intends to call a meeting of senior aviation officials next month to discuss the issue.