The families of victims of the MH370 disaster are urging Malaysia to accept a 'no-win-no-fee'-style offer of a new search for the missing plane.

Voice370, a support group for families of the victims, said specialist US firm Ocean Infinity "would like to be paid a reward if and only if it finds the main debris field".

"Why hasn't Malaysia accepted this win-win offer?" the group said in a statement.

Grace Nathan, a Malaysian lawyer whose mother was on the plane, said: "We are constantly in limbo. They (authorities involved in the search) do not engage us. It is upsetting and frustrating. We are always kept in the dark."

The search for conclusive proof of where the Malaysia Airlines plane crashed was called off in January - nearly three years after the aircraft went missing after making a huge diversion from its flight-path from Kuala Lumpur to Beijing on March 8th 2014.

Malaysia, Australia and China had together scoured 46,000 square miles (120,000 sq km) of remote seabed but failed to find any trace of the Boeing 777, which had 239 people on board.

The cause of the crash remains a mystery.

French police officers inspect a piece of debris from Malaysia Airlines flight 370 in Saint-Andre, Reunion Island in 2015 | Image: Lucas Marie / AP/Press Association Images

Based on analysis of Boeing 777 debris that has washed up on western Indian Ocean beaches, it is believed that the flight most likely crashed in a different area.

The proposed new search zone is estimated to be 9,700 square miles (15,600 sq km) in size on the northern boundary of the last search zone, far southwest of Australia.

But the three countries say the newly-identified area is too big to justify resuming the publicly-funded search.

Ocean Infinity, a US firm based in Texas, uses high-tech deep-sea drones fitted with sonar equipment the seabed at depths of up to 6,000m (19,700ft).

The company said of the deal it proposed in April: "Ocean Infinity have offered to take on the economic risk of a renewed search.

"We're in a constructive dialogue with the relevant authorities and are hopeful that the offer will be accepted," the company said.

Malaysian officials have not commented on the latest developments, but the country's Deputy Transport Minister Aziz Kaprawi previously said the agreement of China, where most of the passengers came from, and Australia, would be needed for a deal to be reached.

Only three fragments of MH370 have been found on western Indian Ocean shores, including a two-metre wing part known as a flaperon.