More than 100 days after a Malaysia Airlines jet went missing search authorities admit they have been looking in the wrong place.

Based on new satellite projections, the Australian-led search operation will now focus on a 60,000 square kilometre area further south in the Indian Ocean.

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It has also been confirmed for the first time that the Boeing 777, carrying 239 people, was set to autopilot several hours before its demise into desolate and unmapped waters.

“Certainly for its path across the Indian Ocean we are confident that the aircraft was operating on autopilot until it ran out of fuel,” Australian Transport Safety Bureau boss Martin Dolan said.

An aerial search for the missing plane has been abandoned, with the wreckage thought to have sunk.

After taking off from Kuala Lumpur on March 8 the aircraft diverted from tracking toward its Beijing destination.

While Australian authorities have not tried to determine when the fateful path was set, Mr Nolan said it diverted west of Sumatra and then travelled in a straight line, suggesting autopilot was engaged.

The new search area, about 1800km from the West Australian coast, has been the subject of an aerial search previously, but efforts will now head below the waves, combing the ocean floor which is some 5km deep in parts.

It will take about three months to map the ocean floor.

Australia will call for tenders to conduct the underwater search, which will begin in August and will be a long and painstaking process, Deputy Prime Minister Warren Truss said.

“We could be fortunate and find it in the first hour or the first day, but it could take another 12 months,” he told reporters in Canberra on Thursday.

Defending fruitless previous search efforts, Mr Truss said little is known of much of the southern Indian Ocean.

“The search area has at all times been based on the best information analysis available,” he said.

“We owe it to the passengers and the crew and everyone who is associated with MH370 to bring this mystery to a conclusion.”

International experts have worked to outline the latest area of interest, which Mr Truss said is the “most likely place where the aircraft is resting”.

“We owe it to the passengers and the crew and everyone who is associated with MH370 to bring this mystery to a conclusion,” he said.

Six Australians were among those on board MH370.

Australia remains dedicated to solving “this greatest aviation mystery”, but Mr Truss could not say how much the search efforts to date have cost.