A private US company will start a new search for the remains of Malaysia Airlines Flight MH370, whose disappearance in 2014 remains one of aviation's biggest mysteries.

The high-stakes deal, struck on Wednesday between Houston-based survey company Ocean Infinity and the Malaysian government, could yield a finder's fee of up to $70 million, or zero if it comes up empty.

The search, which was expected to last for 90 days, will focus initially on a 25,000-square-kilometer zone in the northern Indian Ocean identified by the Australian Transport Safety Bureau.

At a signing ceremony in Putrajaya, Malaysia, on Wednesday, Malaysian Transport Minister Liow Tiong Lai said: "There's an 85 percent probability of finding the wreckage at this new area."

On March 8, 2014, MH370 carrying 239 people－two thirds of whom were Chinese－en route from Kuala Lumpur, Malaysia, to Beijing disappeared from radar screens while over the South China Sea.

Investigators said the plane continued to fly for several hours, turning back over Malaysia and then over the Indian Ocean.

Theories to explain the plane's disappearance include the possibility that it ran out of fuel or the pilot deliberately crashed.

In what's become the most expensive search in aviation history, 26 countries have contributed planes, ships, submarines and satellite time to the effort, according to Reuters.

Previous search efforts, focused in the southern Indian Ocean, began in March of 2014 and lasted more than three years at a cost of more than $150 million.