Investigators say missing Malaysian jet may have disintegrated in mid-air
International police agency Interpol confirmed that at least two passports recorded in its database as lost or stolen were used by passengers on the flight, raising suspicions of foul play.
An Interpol spokeswoman said a check of all documents used to board the plane had revealed more "suspect passports" that were being further investigated. She was unable to say how many, or from which country or countries.
Nearly 48 hours after the last contact with Flight MH370, mystery still surrounded its fate. Malaysia's air force chief said the Beijing-bound airliner may have turned back from its scheduled route before it vanished from radar screens.
"The fact that we are unable to find any debris so far appears to indicate that the aircraft is likely to have disintegrated at around 35,000 feet," a source involved in the investigations in Malaysia told Reuters.
If the plane had plunged intact from close to its cruising altitude, breaking up only on impact with the water, search teams would have expected to find a fairly concentrated pattern of debris, said the source, speaking on condition of anonymity because he was not authorised to discuss the investigation publicly.
Asked about the possibility of an explosion, such as a bomb, the source said there was no evidence yet of foul play and that the aircraft could have broken up due to mechanical causes.
Dozens of military and civilian vessels have been criss-crossing waters beneath the aircraft's flight path, but have found no confirmed trace of the lost plane, although oil slicks have been reported in the sea south of Vietnam and east of Malaysia.
The Civil Aviation Authority of Vietnam said on its website that a Vietnamese navy plane had spotted an object in the sea suspected of being part of the plane, but that it was too dark to be certain. Search planes were set to return to investigate the suspected debris at daybreak.
"The outcome so far is there is no sign of the aircraft," Malaysian civil aviation chief Azharuddin Abdul Rahman said.
"On the possibility of hijack, we are not ruling out any possibility," he told reporters.
The Malaysian authorities said they were widening the search to cover vast swathes of sea around Malaysia and off Vietnam, and were investigating at least two passengers who were using false identity documents.
The passenger manifest issued by the airline included the names of two Europeans - Austrian Christian Kozel and Italian Luigi Maraldi - who, according to their foreign ministries, were not on the plane. Both had apparently had their passports stolen in Thailand during the past two years.
The BBC reported that the men falsely using their passports had purchased tickets together and were due to fly on to Europe from Beijing, meaning they did not have to apply for a Chinese visa and undergo further checks.
An employee at a travel agency in Pattaya, in Thailand, told reporters the two had purchased the tickets there.
The 11-year-old Boeing 777-200ER, powered by Rolls-Royce Trent engines, took off at 12:40 a.m. on Saturday(1640 GMT Friday) from Kuala Lumpur International Airport, with 227 passengers and 12 crew on board.
It last had contact with air traffic controllers 120 nautical miles off the east coast of the Malaysian town of Kota Bharu. Flight tracking website flightaware.com showed it flew northeast after takeoff, climbed to 35,000 ft (10,670 metres) and was still climbing when it vanished from tracking records.
The airline has said 14 nationalities were among the passengers, including at least 152 Chinese, 38 Malaysians, seven Indonesians, six Australians, five Indians, four French and three Americans.