A ship that will hunt for missing Malaysia Airlines Flight MH370 has deployed to its Indian Ocean search zone, according to Malaysia's transport minister and ship tracking data, raising hopes of solving one of aviation's greatest mysteries.

In December, Malaysia agreed to resume the search for the Boeing 777 that was carrying 227 passengers and 12 crew when it vanished en route from Kuala Lumpur to Beijing on March 8, 2014.

Malaysia has not yet signed off on the contract to search the seabed for wreckage, however, casting uncertainty over whether a search has begun.

US exploration firm Ocean Infinity, which conducted the last search for the plane that ended in 2018, said it had no information to provide at this stage.

Malaysia had not yet signed the contract with Ocean Infinity, Transport Minister Anthony Loke said, but he welcomed the company's "proactiveness" to deploy its ships to that area to begin the search.

"Since Ocean Infinity already started to mobilise their ships, of course we welcome it because we have given the principle approval for the search to resume and just need to finalise the contract," Loke told a press conference.

The search would not be open-ended, however, he warned.

"It is not indefinite; there is a certain timeframe given for the contract. These are the details that we need to finalise before we sign," Loke added.

Refinitiv ship tracking data shows one of Ocean Infinity's ships, Armada 78 06, began tracking on Sunday a part of the Southern Indian Ocean, about 2,000 km (1,200 miles) off Australia's west coast.

Ocean Infinity's proposal to resume the search will see it expand the previous search area by 15,000 sq km (5,790 sq miles) in an effort lasting 18 months, with the period from January to April offering the best window, Malaysia said in December.

No precise location of the new search area was given at the time.

Ocean Infinity was "very confident that the current search area is more credible ... This is the area that they have missed in the past," Loke added.

Decade-long hunt

Malaysia engaged Ocean Infinity in 2018 to search in the southern Indian Ocean, but two attempts failed.

They followed an underwater search by Australia, China and Malaysia over an area of 120,000 sq km (46,332 sq mile) of the southern Indian Ocean, based on records of automatic connections between an Inmarsat satellite and the aircraft.

MH370's last transmission was about 40 minutes after it took off from Kuala Lumpur for the Chinese capital. The pilots signed off as the plane entered Vietnamese air space over the Gulf of Thailand and soon after its transponder was turned off.

- Reuters

Military radar showed the plane left its flight path to fly back over northern Malaysia and then out into the Andaman Sea before turning south, when all contact was lost.

Debris, some confirmed and some believed to be from the aircraft, has since washed up along the coast of Africa and on islands in the Indian Ocean.

Victims' relatives have demanded compensation from Malaysia Airlines, Boeing, aircraft engine maker Rolls-Royce and the Allianz insurance group, among others.

A 495-page report into the disappearance in 2018 said the Boeing 777's controls were probably deliberately manipulated to go off course, but investigators could not determine who was responsible and stopped short of offering a conclusion on what happened, saying that depended on finding the wreckage.

Investigators have said there was nothing suspicious in the background, financial affairs, training and mental health of both the captain and co-pilot.

What is known

The last transmission from the plane was about 40 minutes after it took off from Kuala Lumpur for Beijing.

Captain Zaharie Ahmad Shah signed off with "Good night, Malaysian three seven zero", as the plane entered Vietnamese airspace.

Shortly thereafter, its transponder was turned off, which meant it could not be easily tracked.

Military radar showed the plane left its flight path to fly back over northern Malaysia and Penang Island, and then out into the Andaman Sea towards the tip of the Indonesian island of Sumatra. It then turned south and all contact was lost.

Underwater searches

Malaysia, Australia and China launched an underwater search in a 120,000 sq km (46,332 sq miles) area in the southern Indian Ocean, based on data of automatic connections between an Inmarsat satellite and the plane.

The search, which cost about A$200 million ($143 million), was called off after two years in January 2017, with no traces of the plane found.

In 2018, Malaysia accepted a "no-cure, no-fee" offer from U.S. exploration firm Ocean Infinity for a three-month search, meaning the company would only get paid if it found the plane.

That search covered 112,000 sq km (43,243 square miles) north of the original target area and also proved fruitless, ending in May 2018.

Debris

More than 30 pieces of suspected aircraft debris have been collected along the coast of Africa and on islands in the Indian Ocean, but only three wing fragments were confirmed to be from MH370.

Most of the debris was used in drift pattern analysis in the hopes of narrowing down the aircraft's possible location.

Investigation report

A 495-page report into MH370's disappearance, published in July 2018, said the Boeing 777's controls were likely deliberately manipulated to take it off course, but investigators could not determine who was responsible.

The report also highlighted mistakes made by the Kuala Lumpur and Ho Chi Minh City air traffic control centres and issued recommendations to avoid a repeat incident.

Investigators stopped short of offering any conclusions about what happened to MH370, saying that depended on finding the plane's wreckage.

Conspiracy theories

The inability to locate MH370's crash site has fuelled numerous conspiracy theories, ranging from mechanical error or a remote-controlled crash, to more bizarre explanations like an alien abduction or a Russian plot.

In recent years, some aviation experts have said the most likely explanation was that the plane was deliberately taken off course by an experienced pilot.

But investigators have said there was nothing suspicious in the background, financial affairs, training and mental health of both captain and co-pilot.