Malaysia Airlines plane still missing

Vietnam has scrambled rescue helicopters to check a 'yellow object' floating in its waters that rescue teams suspect could be a life raft from the missing Malaysian Airlines plane, a minister said on Monday.

A Vietnamese jet had seen the object earlier on Monday but was unable to get close enough to determine what it was, Pham Quy Tieu, Vice Transport Minister and deputy head of the country's rescue committee, told Reuters.

The Civil Aviation Authority of Vietnam said on its website searches were being conducted about 140 km (90 miles) southwest of Tho Chu island, which is located about 200 km off the coast of southern Vietnam.

Authorities had earlier said no trace of the missing passenger jet had been found after search and rescue teams had been unable to find what was believed to be part of a door spotted yesterday afternoon.

As Interpol investigates whether up to four passengers boarded the plane using stolen passports, it was today revealed five passengers checked on to the flight but did not board the plane. Their baggage was removed before it departed, he said.

The Boeing 777 went missing early on Saturday morning on a flight from Kuala Lumpur to Beijing with 239 people on board.

Malaysia's civil aviation chief Azharuddin Abdul Rahman described the disappearance of the plane as an 'unprecedented aviation mystery'.

He said a hijacking could not be ruled out as investigators explore all theories for the loss of Malaysia Airlines flight MH370 en route to Beijing.

'Unfortunately we have not found anything that appears to be objects from the aircraft, let alone the aircraft,' he told a news conference.

'As far as we are concerned, we have to find the aircraft, we have to find a piece of the aircraft if possible.'

As dozens of ships and aircraft from seven countries scour the seas around Malaysia and south of Vietnam, questions mounted over possible security lapses and whether a bomb or hijacking could have brought down the Boeing airliner.

It comes as Interpol criticised Thailand's lax airport security after it emerged at least two passengers' passports were stolen, prompting fears that terrorists might have used them to get on board the Malaysia Airlines flight MH307

The possibility of a further two stolen passports used on the same flight is now being investigated after it emerged that no cross checks were carried out against Interpol's lost and stolen database.

Procedural checks would have revealed that at least two passengers were travelling on stolen passports stolen.

Malaysian authorities now believe they have CCTV images of the two men using the stolen passports to board the flights.

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 it may have turned back from its scheduled route before it disappeared.

A senior source involved in preliminary investigations in Malaysia said the failure to quickly find any debris indicated the plane may have broken up mid-flight, which could disperse wreckage over a very wide area.

'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,' said the source.

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.

Still, the source said the closest parallels were the explosion on board an Air India jetliner in 1985 when it was over the Atlantic Ocean and the Lockerbie air disaster in 1988. Both planes were cruising at around 31,000 feet when bombs exploded on board.