Officials in Malaysia are focusing on 'mid-air disintegration' as the possible cause for the disappearance of the Malaysian Air jetliner on Saturday morning.

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The investigation into the disappearance of the plane its 239 passengers is "narrowing" on this theory, Malaysian officials said.

Piece of a door and airplane tail have been discovered by Vietnamese Navy search teams looking for lost Malaysian plane. Officials say they are verifying the findings.

A Vietnamese plane searching for the lost Malaysian Airlines jetliner has discovered what they believe to be a piece of a composite inner door and a piece of the tail belonging to the aircraft. Vietnam’s ministry of information and communication broke the news in a posting on its website.

The pieces were located about 50 miles south-southwest of Tho Chu island. Malaysia Airline said it had received no confirmation about the identity of the fragments.

Nightfall in the region prevented further identification work – expected to continue on Monday.


Interpol examining suspect passports

Interpol says it is of "great concern" that at least two passengers were able to board missing Malaysia Airlines flight 370 with fake passports, and is "examining additional suspect passports."

The international police agency confirmed that at least two of the passports used to board the missing flight, which disappeared in the early hours of Saturday morning, were stolen or lost.

Interpol added that no checks had been made in its databases of passports stolen from an Austrian and an Italian between the times when they were stolen and the the departure of the flight.

"Whilst it is too soon to speculate about any connection between these stolen passports and the missing plane, it is clearly of great concern that any passenger was able to board an international flight using a stolen passport listed in Interpol's databases," Interpol Secretary General Ronald Noble said in a statement.

Malaysia’s police chief, Inspector-General Khalid Abu Bakar, told reporters that while police investigators “don’t dismiss the possibility” of terrorism, they weren’t considering it the most likely cause for the disappearance of MH370.

An unheard-of group called the Chinese Martyrs’ brigade have claimed responsibility for the Malaysia Airlines plane crash in a pdf statement emailed to several journalists in China. However, the statement has been dismissed as having little credibility by the Chinese media.

The statement cites the grievances of China’s Uigher minority people and the territorial and religious persecution they have suffered as the motivation for the attack, but there is no way to verify the claims or prove any connection to the jetliner’s crash.

Turned back?

It was also reported on Sunday that the lost Malaysia Airlines plane may have turned back before crashing, or may have suffered a sudden catastrophic event.

The Malaysian authorities have widened the area where they are searching for flight MH370, after radar evidence shows it may have turned back before crashing into the South China sea.

The Boeing 777 flight from Kuala Lumpur to Beijing has been missing for 36 hours. Malaysia Airlines said it was "fearing the worst" for the plane’s 239 passengers.

Meanwhile authorities are no closer to determining how or why the plane disappeared, and why no distress communications of any kind were made.

Authorities including the US are also unsure whether the presence of four people on the plane with false passports is significant, or not.

Read more: How can a plane just vanish? 

Spilt oil but no plane

Searchers off the coast of Vietnam found oil slicks on Saturday, the day after the plane was reported missing, the Malaysian transport minister confirmed. But searches there through the day have revealed no wreckage or debris as yet.

Four passports on plane suspect

Malaysian and US investigators are looking into revelations that two passengers were travelling on stolen European passports – one Italian and one Austrian – and that a further two passengers on board the flight also had fake id.

All four booked through China Southern Airlines, which was code-sharing the flight with Malaysia Airlines, a Malaysian official with knowledge of the investigation said. The two on Italian and Austrian passports had booked the flight as part of a three leg trip to destinations in Europe. It is understood that they booked the flight the day before.

It means that four people had boarded the flight with fake identification. Malaysian airport authorities are scanning airport CCTV to identify the mystery passengers.

"All the four names are with me," Hishamuddin Hussein, a Malaysian defence and transport minister, told reporters. He confirmed that Malaysian investigators had met counterparts from the U.S. FBI, and said the investigation was focusing on the entire passenger manifest - the list of people recorded who actually boarded the plane.

Mystery over tragic disappearance

Foul play aside, no more has been revealed about how the plane could disappear without trace. The model of airline has an almost impeccable safety record, and Malaysia Airlines is one of the safest carriers in Asia. Weather conditions were fine and the accident would seem to have occurred at one of the safest parts of a journey – while it was cruising.

Others speculated it must have been a sudden catastrophic event that brought the plane down leaving no time for MayDay calls.

John Goglia, a former board member of the National Transportation Safety Board, the U.S. agency that investigates plane crashes, said the lack of a distress call suggested that the plane either experienced an explosive decompression or was destroyed by an explosive device.

"It had to be quick because there was no communication," Goglia said. He said the false identities of the two passengers was "a big red flag".

Downed Pilot loved Boeing 777s

Friends of the pilot of the downed plane pilot Zaharie Ahmad Shah, 53 said he was extremely experienced.

"He knew everything about the Boeing 777. Something significant would have had to happen for Zaharie and the plane to go missing. It would have to be total electrical failure," said another Malaysia Airlines pilot who knew Zaharie. Malaysia Airlines staff could not be named according to company policy.