Malaysia's government secretly believed "very early on" the MH370 mystery was a mass murder-suicide orchestrated by the captain, Australia's ex-prime minister has claimed.
The Malaysia Airlines jet was carrying 239 passengers and crew when it vanished during a flight from Kuala Lumpur to Beijing on March 8, 2014.
The captain of the Boeing 777 was Zaharie Ahmad Shah who has been accused of hijacking the aircraft and crashing it in the remote Indian Ocean in a carefully planned plot.
Malaysia 's official report said there was no evidence Zaharie had carried out a murder-suicide, but it was branded a cover-up and, in a new interview, Tony Abbott claims the "highest levels" of the Southeast Asian country's government believed that theory early on.
Mr Abbott, who was Australia's prime minister at the time, told Sky News: “My understanding, my very clear understanding, from the very top levels of the Malaysian Government is that from very, very early on here they thought it was a murder suicide by the pilot.
“I’m not going to say who said what to whom, but let me reiterate – I want to be absolutely crystal clear – it was understood at the highest levels that this was almost certainly murder-suicide by the pilot.
"A mass murder-suicide by the pilot.”
Mr Abbott said officials never mentioned any alternative theories to him.
Malaysia hit back at the claims, saying there was no evidence to support the murder-suicide theory and the exact cause of the disappearance cannot be determined because the plane is still missing.
Last year, one of Zaharie's lifelong friends, a fellow pilot, revealed that the captain likely locked his inexperienced co-pilot out of the cockpit and deliberately crashed the passenger jet into the sea.
The friend said he believed Zaharie was guilty of an atrocity and "it’s the necessary conclusion" to one of the world's greatest aviation mysteries.
Data analysis indicates the Boeing 777-200ER flew over the Indian Ocean until it ran out of fuel and violently slammed into the water.
There was a suspicion that Shah - who flew a similar path on his flight simulator at home - was clinically depressed.
His voice was heard in the final radio communication less than two minutes before the plane began to divert from its flight path.
He said: “Good night. Malaysian three-seven-zero.”
The electrical system was deliberately turned off, making the plane impossible to track by satellite.
Earlier this month, Australia's News Corp claimed a new search could begin this year based on new evidence that it said showed the plane could have ended up in an area adjacent to the previous search area in the Indian Ocean.
The report said US exploration firm Ocean Infinity was in discussions with the Malaysian government to mount a new search on a no find,no fee basis.
But Malaysia said it had not received any new credible evidence to initiate a new search.
Ocean Infinity chief executive officer Oliver Plunkett said at the time that "no new search is imminent", but the firm continues to engage with experts to identify where any new search might be launched.
He told Reuters: "The Malaysian Government, rightly in our view, set a high bar before they will engage in that discussion.
"It was and remains our position that we hope to be able to offer our services to the Malaysian government again at some point in the future."
Malaysia, China, and Australia, called off a two-year, £100million underwater search in the southern Indian Ocean in January 2017 after finding no trace of the aircraft.
A second three-month search, led by Ocean Infinity, ended similarly in May the following year.
