Australia on Monday brushed off a reported FBI probe into the pilot of missing flight MH370, saying it was a matter for Malaysia and did not shed light on the plane's location.

The New York magazine Friday cited a secret FBI document showing the jet's captain Zaharie Ahmad Shah used his elaborate home-built flight simulator to chart a route similar to the one believed taken by the doomed plane just weeks before it disappeared.

The revelation reignited speculation in the Australian media Monday that the unsolved mystery could have been a murder/suicide.

"I'm aware, as is the government, of the reports about the FBI investigation into the MH370 captain's home simulator," Prime Minister Malcolm Turnbull said in Sydney.

"I'm unable to comment on them other than to say that it's a matter for the Malaysian investigators when they're considering their final report into this tragedy."

But he added: "I just note that even if the simulator information does show that it is possible or very likely that the captain planned this shocking event, it does not tell us the location of the aircraft."

Australia has been leading the massive search for the Malaysia Airlines plane which is believed to have gone down in the southern Indian Ocean after vanishing on March 8, 2014 en route from Kuala Lumpur to Beijing with 239 people aboard.

With the designated 120,000-square-kilometre (46,000-square-mile) search zone almost scoured, Malaysia, China and Australia agreed last week the hunt will be suspended if nothing turns up.

READ: Wrong search area for MH370?

Search authorities say satellite data indicated the plane went down somewhere in that remote and stormy ocean far off Western Australia with the Malaysian government maintaining it does not know what caused the tragedy.

According to a confidential document from Malaysian police investigating the incident obtained by the New York magazine, the FBI recovered deleted data points from the flight simulator on Zaharie's hard drive.

"We found a flight path, that lead to the southern Indian Ocean, among the numerous other flight paths charted on the flight simulator, that could be of interest," the document said, according to the magazine.

Although the paths are similar, the simulated flight's endpoint is located some 900 miles (1,450 kilometres) from the area where the plane is believed to have gone down, it said.

At the time of the crash Zaharie came under scrutiny amid unsubstantiated reports that he was upset over a jail sentence handed to Malaysian opposition leader Anwar Ibrahim hours before the plane took off or was suicidal due to personal problems.

But his family and friends strongly reject such claims as baseless.

Turnbull said everyone involved "earnestly, passionately wants to find the aircraft".

"I hope it will be found, but at this point it is an unknown. It has an element of mystery but, above all, a deep sense of tragedy and loss."