The Malaysian government agreed on Wednesday to pay U.S. seabed exploration firm Ocean Infinity Ltd. from $20 to $70 million on condition that it finds the missing Malaysia Airlines flight MH370 within 90 days.

The two parties sealed the "no cure, no fee" deal wherein the U.S. firm will scour a new search area covering 25,000 square kilometers in the southern Indian Ocean beginning mid-January.

Under the agreement, Malaysia Transport Minister Liow Tiong Lai told a press conference, Ocean Infinity must identify the debris field and/or locate the flight data recorder and cockpit voice recorder.

The payment terms are that $20 million will be paid if the wreckage and flight recorders are found within the first 5,000 sq km; $30 million within an additional 10,000 sq km; $50 million within a further 10,000 sq km and $70 million for search beyond 25,000 sq km.

"Based on experts' view there is 85 percent probability of finding the wreckage at the new area," Liow said.

The Boeing 777 vanished from radar less than 40 minutes after taking off from Kuala Lumpur International Airport just after midnight on March 8, 2014, heading to Beijing with 239 people on board.

Ocean Infinity has already dispatched a vessel, Seabed Constructor, that left South African port of Durban last Tuesday to take advantage of the favorable weather conditions in the southern Indian Ocean.

The vessel is carrying eight submersibles equipped with side scan sonar and other high-technology gadgets and capable of operating in waters up to 6,000 meters deep.

Chief Executive Oliver Plunkett said the vessel is expected to arrive on site on Jan. 17.

"I think we have a realistic prospect," he told reporters.

The submersibles or "autonomous underwater vehicles," as the firm call them, can cover 1,200 sq km a day and the entire 25,000 sq km within three to four weeks.

Based on radar and satellite communications, the plane was calculated to have plunged into the southern Indian Ocean, sparking a massive hunt led by Australia.

After nearly three years of combing 120,000 sq km of ocean floor without success, the Malaysian, Chinese and Australian governments in January last year decided to suspend the search until "credible new information" becomes available.

Family members of those who were on board, of whom over two-thirds were Chinese, had protested the suspension and pleaded for the authorities to consider the findings from the Australian-based Commonwealth Scientific and Industrial Research Organization, which in December 2016 identified a potential resting place for the jumbo jet within a 25,000 sq km area.

CSIRO had made the calculation based on the drift patterns of the flaperon, the first debris belonging to the ill-fated flight that was found in 2015 on the French island of Reunion, east of Madagascar.

News of the resumption of search was welcomed by family members.

"We are hopeful. This is what we have been waiting for. We pray for closure. It has been four years of just waiting," Elaine Chew, 38, wife of Malaysia Airlines flight steward Tan Sze Hiang who was one of 12-member cabin crew, told Kyodo News.

Their daughter had planned to celebrate her fifth birthday on March 14, 2014 with her father, but he never returned.