A boy watches a plane on the runway on the morning of the final MH17 flight arriving at Kuala Lumpur International Airport July 25, 2014. [Photo/Agencies]

SYDNEY - Government ministers from Australia, China and Malaysia on Thursday said that they would extend the search for missing Malaysia Airlines Flight MH370 by an additional 60,000 sq miles if the wreckage is not found in the current search area.

The extended search for the jetliner, which disappeared last year but is believed to have crashed in the Indian Ocean off Australia's west coast, could take up to a year, officials said at a meeting in Kuala Lumpur.

Malaysian Transport Minister Liow Tiong Lai, Australian Deputy Prime Minister Warren Truss and Chinese Transport Minister Yang Chuantang pledged to double the current search area if necessary.

"Should the aircraft not be found within the current search area, ministers agreed to extend the search by an additional 60,000 square kilometres to bring the search area to 120,000 square kilometres and thereby cover the entire highest probability area identified by expert analysis," they said in a joint statement.

"Ministers recognise the additional search area may take up to a year to complete given the adverse weather conditions in the upcoming winter months."

No trace has been found of the Boeing 777 aircraft, which disappeared last March carrying 239 passengers and crew, in what has become one of the greatest mysteries in aviation history.

MH370 vanished from radar screens shortly after taking off from Kuala Lumpur, bound for Beijing. Investigators believe it was flown thousands of miles off course before eventually crashing.

The search of a rugged 60,000 sq km (23,000 sq mile) patch of sea floor some 1,600 km (1,000 miles) west of the Australian city of Perth, which experts believe is the plane's most likely resting place, will likely be finished next month.

Four vessels owned by Dutch engineering firm Fugro, equipped with sophisticated underwater drones, have searched more than 60 percent of the previously unmapped expanse of sea floor that has been designated the highest priority.

The ministers seemed to imply that the additional search area could represent the last best opportunity to find the plane.

"Upon completion of the additional 60,000 square kilometres, all high probability search areas would have been covered," they said.

Loss-making Malaysia Airlines, whose fortunes worsened when another of its Boeing 777's was shot down over Ukraine on July 17, killing all 298 people on board, was delisted at the end of 2014 as part of a $1.8 billion government-led restructuring.