China is set to join the underwater search for a Malaysia Airlines passenger jet missing for almost two years by providing a sonar-equipped vessel by the end of February, Australia's deputy prime minister Warren Truss said on Friday.

Malaysia Airlines Flight MH370 disappeared with 239 people on board during a flight from Kuala Lumpur to Beijing in March 2014, sparking one of the greatest mysteries in aviation history.

The Chinese vessel Dong Hai Jiu 101 was offered to Prime Minister Malcolm Turnbull in November and will be deployed to join search operations in the southern Indian Ocean, where the plane is believed to have gone down in March 2014.

At the time, China valued its contribution to the search at A$20 million ($14.2 million).

The Australian-led underwater search is one of the most expensive ever conducted. An initial hunt along a rugged 60,000-sq km (23,000 sq miles) patch of sea floor off the coast of Perth cost A$120 million but yielded no sign of the plane.

The presence of Dong Hai Jiu will take to four the number of vessels scouring a search area that has been expanded to 120,000 square km (46,330 square miles) of ocean floor.

The vessel is expected to leave Singapore for Australia on Jan. 31 and commence operations towards the end of February.

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The sonar system onboard Dong Hai Jiu 101 will be operated by Phoenix International Holdings and Hydrospheric Solutions. Both companies have previous experience in the search for MH370.

Earlier this week, Australian authorities said they had lost a deep-water sonar detector that was being used in the search.

A piece of the plane washed up on the French island of Reunion in the Indian Ocean in July 2015 but no further trace has been found.

On Saturday, a piece of suspected plane wreckage was found off the east coast of southern Thailand but aviation experts and Thai officials said it was unlikely to belong to MH370.

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