KUALA LUMPUR (REUTERS) - Malaysia kicked off a new search for missing Malaysia Airlines Flight MH370 on Monday (Jan 22), its civil aviation department said.

The aircraft disappeared en route from Kuala Lumpur to Beijing in March 2014 with 239 people, mostly Chinese, on board, in one of the world's greatest aviation mysteries.

This month, Malaysia agreed to pay US firm Ocean Infinity up to US$70 million (S$92.4 million) if it finds the plane within 90 days. The search vessel, the Seabed Constructor, set off from Durban, South Africa, on Jan 3. Reuters reported earlier on Tuesday that the Seabed Constructor had reached the remote spot in the Indian Ocean where Australian scientists believe the plane went down.

Australia, Malaysia and China called off their two-year search for the plane a year ago after finding nothing in a 120,000-sq-km underwater search zone.

Investigators believe someone may have deliberately switched off MH370's transponder before diverting it over the Indian Ocean. Debris has been collected from Indian Ocean islands and Africa's east coast and at least three pieces have been confirmed as coming from the missing plane.

Malaysia agreed earlier this month to pay US firm Ocean Infinity up to US$70 million (S$92.4 million) if it finds the plane within 90 days. The search vessel, the Seabed Constructor, set off from Durban, South Africa, on Jan 3.

The vessel is equipped with eight autonomous submersibles that can search a wide area of sea floor much faster than the tethered scanners used in previous searches, Charitha Pattiaratchi, professor of coastal oceanography at the University of Western Australia, told Reuters by phone from Colombo.

"If they don't find anything in the 90 days ...I think that would be the end for decades - this is like the final effort, if you like," he said.

Reuters data, which is supplied from an automated tracking system, shows the vessel reached the search zone on Sunday (Jan 21) and on Tuesday was tracking towards a spot that Australia's scientific agency believes with "unprecedented precision and certainty" is the most likely location of the aircraft.

Texas-based Ocean Infinity could not be reached outside business hours at offices in Houston and London.

Australia, Malaysia and China called off their two-year search for the plane a year ago after finding nothing in a 120,000-sq-km underwater search zone.