Teams searching for the missing Malaysia Airlines plane are to deploy a robotic submarine for the first time.

Search chief Angus Houston said the Bluefin-21 drone would be sent down as soon as possible to search for wreckage on the sea floor.

Teams have been using a towed pinger locator to listen for signals from the plane's "black box" flight recorders.

But no new signals have been heard since 8 April, amid concerns the flight recorders' batteries have expired.

Flight MH370 went missing on 8 March with 239 people on board. It was flying from Kuala Lumpur to Beijing when it lost contact with air traffic controllers over the South China Sea.

Malaysian officials believe, based on satellite data, that it ended its flight in the southern Indian Ocean, thousands of kilometres off course.