SYDNEY (AFP) - The hunt for missing Malaysia Airlines Flight MH370 will not be expanded beyond its current search area unless there are specific new leads, Australian officials said on Wednesday.

In April, more than a year after the plane vanished en route from Kuala Lumpur to Beijing with 239 mostly Chinese people on board, Malaysia, Australia and China announced that the search zone would double in size.

This boosted the area of the remote southern Indian Ocean being scoured by three specialist vessels to 120,000 sq km.

But it will not be expanded any further, the Australian-led Joint Agency Coordination Centre (JACC) said in an update.

"In the absence of credible new information that leads to the identification of a specific location of the aircraft, governments have agreed that there will be no further expansion of the search area," it said.

The hunt for the aircraft, which disappeared on March 8 last year, has been a complex undertaking, with Australia initially concentrating on a remote 60,000 sq km area of the ocean far off its west coast.

The zone was determined by analysing data from satellite signals which indicate the plane went down in the Indian Ocean after mysteriously diverting.

More than 50,000 square kilometres of the seafloor have been scoured so far with no trace of the jet, JACC said, and with the onset of winter and poor weather the operation is slowing down.

The deep underwater search, using sonar equipment after the ocean floor was closely mapped last year, is currently suspended with waves reaching up to 12 metres (39 feet), although ships remain on the scene.

It will continue once conditions improve but be scaled back with one of the vessels, GO Phoenix, ceasing operations and returning to Singapore near the end of June.

A fourth vessel previously involved in the search, Fugro Supporter, was withdrawn in May amid the worsening conditions.

"Safety of the search crews, as always, remains a priority and vessels and equipment utilised will vary to reflect operational needs, particularly during winter months," JACC said.

"Search operations will continue through the winter months, but pauses are anticipated."