PERTH — International search planes and ships are heading to an area where a Chinese ship twice heard what could be signals from missing Malaysia Airlines Flight MH370's black box locators, Australian search authorities said on Sunday.

Retired Air Chief Marshal Angus Houston, the head of the Australian agency coordinating the operation, told a media conference in Perth that two reported acoustic detections from the Haixun 01 were a good lead but there remained no certainty that they had come from the missing plane.

Aircrews from seven countries have been flying dozens of missions from Perth deep into the southern Indian Ocean looking for debris from the jet and have been joined by ships fitted with sophisticated equipment designed to pick up the locators on the black box voice and data recorders.

The Boeing 777 lost communications and disappeared from civilian radar less than an hour into an overnight flight from Kuala Lumpur to Beijing on March 8.