Welcome to the BBC's live coverage of the search for the missing Malaysia Airlines flight MH370, as an Australian ship detects signals potentially from an aircraft black box data recorder in the Indian Ocean. Stay with us for the latest updates - reports from our correspondents, analysis and your reaction from around the world. You can contact us via email, text or Twitter.
Air Chief Marshal Angus Houston, the head of a joint agency co-ordinating the search in the southern Indian Ocean, warned that it could take days to confirm whether the signals picked up by the Australian navy ship Ocean Shield are indeed from the flight recorders on flight MH370, but called the discovery the "most promising lead" so far.
ACM Houston said the signals were detected using the Towed Pinger Locator deployed on the Ocean Shield. It picked up signals on one occasion for 2 hours and 20 minutes and for a second time for 13 minutes.
Jon Donnison, BBC News, Sydney
tweets: Trying to locate #MH370 signals painstaking work. Ocean Shield dragging Towed Ping Locator on long cable takes 3 hours just to turn round.
ACM Houston said two distinct pinger returns could be heard: "Significantly this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder," he said.
The device on the missing plane that makes those signals is made by US company Dukane Seacom. Its director, Chris Portale, told the BBC Radio 4's Today programme that looking for the MH370 black box was like "looking for a suitcase on the side of a mountain" but under water.
Mr Portale adds: "You've got two potential sites in the area that they are reviewing so I believe they are in the right area. I believe they have got three to four more days of good, solid output - where if they are spending the resources there and they are close by - and one of those hits... is actually real - they have a very good hope of at least spotting the wreckage."
09:00 Richard Westcott, BBC Transport Correspondent
explains in this video exactly what those searching for the plane's wreckage are up against.
The plane, carrying 239 people, was flying from Kuala Lumpur to Beijing on 8 March when it disappeared. Malaysian officials say they believe it crashed in the southern Indian Ocean.