KUALA LUMPUR, Malaysia — Officials from Malaysia, Australia and China said Thursday that they would double the search area for the Malaysia Airlines jet that disappeared more than a year ago if it is not found by the end of next month.

Vessels that have scoured the southern Indian Ocean far off the coast of Australia for months have found no trace of Malaysia Airlines Flight 370, which disappeared on March 8, 2014, with 239 people aboard.

Image From left, Warren Truss, the deputy prime minister of Australia; Liow Tiong Lai, the Malaysian transport minister; and Yang Chuantang, the Chinese transport minister, at a news conference on Thursday in Kuala Lumpur, Malaysia. Credit... Mohd Rasfan/Agence France-Presse — Getty Images

“We are moving to widen out the search area and to extend it in every direction,” Warren Truss, Australia’s deputy prime minister, said after a meeting here with Liow Tiong Lai and Yang Chuantang, the Malaysian and Chinese transportation ministers.