Lost jet: Who were mystery passengers?

The disappearance of a Malaysian airliner about an hour into a flight to Beijing was an "unprecedented mystery", Azharuddin Abdul Rahman, head of Malaysia's Civil Aviation Authority, said yesterday as a massive air and sea search - now in its third day - failed to find any trace of the plane or the 239 people on board.

Dozens of ships and aircraft from 10 countries scoured the seas around Malaysia and south of Vietnam as questions mounted about the possibility of security lapses and whether a bomb or a hijacking attempt could have brought down the Boeing 777-200ER, which took off from the Malaysian capital, Kuala Lumpur.

A senior police official said people armed with explosives and carrying false identity papers had tried to fly out of Kuala Lumpur in the past and that current investigations were focused on two passengers on the missing plane who carried stolen passports.

"We have stopped men with false or stolen passports and carrying explosives who have tried to get past [airport] security and get onto a plane," he said.

"There have been two or three incidents but I will not divulge the details."

Azharuddin said a hijacking attempt could not be ruled out as investigators explored all credible theories.

"Unfortunately, we have not found anything that appears to be from the aircraft, let alone the aircraft itself," he said. "As far as we are concerned, we have to find the aircraft. We have to find a piece of the aircraft."

Azharuddin said the two men with stolen passports did not look like Asians but did not elaborate. Airport CCTV footage showed they complied with all security procedures, he said.

"We are looking at the possibility of a stolen-passport syndicate," he said.

About two-thirds of the 227 passengers and 12 crew now presumed dead aboard the plane were Chinese. The airline said other nationalities included 38 Malaysians, seven Indonesians, six Australians, five Indians, four French and three Americans.

China urged Malaysia to speed up the search for the plane.

"We hope the Malaysians understand the urgency for China, especially of the family members, and can step up the speed of the investigation and increase search and rescue efforts," Foreign Ministry spokesman Qin Gang said.

A senior source involved in preliminary investigations in Malaysia said the failure to find debris indicated that the plane might have broken up in flight, and the wreckage was dispersed over a very wide area.

"The fact that we are unable to find any debris indicates that the aircraft is likely to have disintegrated at around 10000m," said the source.

Asked about the possibility of an explosion, he said there was no evidence of foul play and that the aircraft could have broken up because of a mechanical fault.

The source said the closest parallels were the bomb explosions on board an Air India jetliner in 1985 over the Atlantic, and on a Pan Am aircraft over the Scottish town of Lockerbie in 1988. Both planes were cruising at about 9500m.

The US extensively reviewed imagery taken by its spy satellites for evidence of a mid-air explosion but saw none, a US government source said.

The source described US satellite coverage of the region as thorough.

No distress signal was sent from the lost plane, which experts said suggested a sudden catastrophic failure or explosion, but Malaysia's air force chief said radar tracking showed that it might have turned back from its scheduled route before it disappeared.