Perth: The searchers hunting for the missing Malaysian jet are "very confident" that a series of underwater signals detected in a remote part of the Indian Ocean were from the aircraft's black box, the Australian Prime Minister said today.

A handout  photo taken on April 4, 2014, and released on April 5 by Australian Defence shows the towed pinger locator being towed by Australian Defence Vessel Ocean Shield in the first search for the missing flight data recorder and cockpit voice recorder of Malaysia Airlines flight MH370 in the southern Indian Ocean. Pic: AFP