A fourth ship with specialized underwater sonar equipment will join the search for a Malaysia Airlines jet 10 months after it vanished under mysterious circumstances, an Australian official said Monday.

The ship Fugro Supporter was on its way to the search area after conducting trials off the Indonesian island of Bali, Australian Deputy Prime Minister Warren Truss said in a statement.

"Fugro Supporter has been equipped with a Kongsberg HUGIN 4500 autonomous underwater vehicle," the statement said. "The AUV will be used to scan those portions of the search area that cannot be searched effectively by the equipment on other vessels."

Not a single trace of Malaysia Airlines Flight 370 has been found since the Boeing 777 vanished with 239 people aboard on March 8 last year during a flight from Kuala Lumpur to Beijing.

The jetliner veered sharply off course and flew for hours with its communications systems disabled before disappearing.

Three ships — two provided by a Dutch contractor and one from Malaysia — have already been scouring 60,000-square-kilometre area of the Indian Ocean about 1,800 kilometres west of Australia.

Since October, the ships have searched more than 12,000 square kilometres of the seafloor with towed sonar equipment — or one-fifth of the highest-priority search zone.

Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, the agency leading the search, said the unmanned submarine equipment would be used to take a second, closer look at difficult seabed terrain where towed sonar was less thorough.

"Because the terrain remains complex, there's a possibility that there'll be some areas that we can't do with the towed sonar, and so we're getting an autonomous underwater vehicle as the alternative option," Dolan said. "We think we've got pretty good coverage already, but this will give us a 100 per cent guarantee."

The underwater drone moves slower than the towed sonar equipment and will not hasten the search, which is expected to end around May if nothing is found earlier, Dolan said.

No additional equipment will be needed to ensure a thorough search of the mountainous terrain, which ranges from 600 metres to 6.5 kilometres deep, he said.

The Fugro Supporter is jointly funded by the Australian and Malaysian governments. It is expected to join the search in late January, Truss said.