MH370 search has 'best lead so far'

The towed pinger locator (TPL-25) is towed behind the Australian Defence Vessel Ocean Shield in the southern Indian Ocean during the search for the flight data recorder and cockpit voice recorder of the missing Malaysian Airlines flight MH370 in this picture released by the Australian Defence Force April 5, 2014. Photo: Reuters

An Australian vessel searching for the missing Malaysia Airlines plane has detected signals consistent with those from aircraft black boxes.

Australian defence vessel Ocean Shield acquired the signal twice, once for more than two hours, Australia said.

Air Chief Marshal Angus Houston, who is leading the search, called it the "most promising lead" so far.

But he said more information was needed: "We haven't found the aircraft yet and we need further confirmation."