Malaysia has said the search area for missing Flight 370 will be expanded by another 60,000 square kilometres (23,000 square miles) in the Indian Ocean if the airliner is not found by May.

Transport minister Liow Tiong Lai said Malaysia, Australia and China, which are leading the search for the Boeing 777 that went missing on March 8 last year, are "committed to the search".

After meeting his counterparts from the other two countries, he said 61 per cent of the current search area had so far been scoured off Australia's west coast. The remaining area will have been covered by the end of May, he said.

"If the aircraft is not found within the 60,000 square kilometres, we have collectively decided to extend the search to another 60,000 square kilometres within the highest probability area," he said.

He added that the two areas together would cover 95 per cent of the Indian Ocean flight path of the plane, which went missing on a flight from Kuala Lumpur to Beijing with 239 people on board.

It dropped off radar, and investigators later figured out that it made a series of turns and headed in the opposite direction from where it was heading before crashing into the Indian Ocean.