Acoustic signals intercepted in early April had probably not originated in black boxes of the missing Malaysia Airlines Flight 370, experts have concluded after a complex seabed scan failed to spot any signs of wreckage.
The news was announced after the Bluefin 21 unmanned underwater drone concluded the search of the area determined as the likeliest resting place of Flight MH370, based on the analysis of the acoustic signals.
"The Australian Transport Safety Bureau (ATSB) has advised that the search in the vicinity of the acoustic detections can now be considered complete and, in its professional judgment, the area can now be discounted as the final resting place of MH370," the agency in charge of the search said in a statement.
Experts still believe the pings, which led to the search teams focusing on that particular area, some 850 square kilometres in size, came from an artificial source but are puzzled about their actual origin.
"We don't know what those pings were," ATSB chief Martin Dolan told Reuters. "We are still analysing those signals to understand them better."
On Thursday, CNN quoted Michael Dean, the US Navy's deputy director of ocean engineering, as saying that authorities now almost universally believed the pings did not come from the plane's on-board data or cockpit voice recorders.
"Our best theory at this point is that (the pings were) likely some sound produced by the ship ... or within the electronics of the Towed Pinger Locator," Dean told CNN.
This outcome is not what the search teams expected when they hailed the signals in early April as the biggest breakthrough in the desperate hunt for the Malaysian Boeing 777-200ER which disappeared from air-traffic control radars in early hours of 8 March, about an hour after take-off from the Kuala Lumpur airport.
"We concentrated the search in that area because the pings were the best information available at the time," Australian Deputy Prime Minister Warren Truss, who is also the transport minister, told the Australian parliament.
"We are still very confident that the resting place of the aircraft is in the southern (Indian) Ocean, and along the seventh ping line," he added, referring to an arc identified by analysis of satellite communications data from UK company Inmarsat.
The search zone, some 1,600km (1,000 miles) off the northwest coast of Australia, has now been extended to a 60,000 sq km zone that is being surveyed by a Chinese vessel. It will then be searched by a commercial operator in a mission that is expected to start in August and take up to a year, at a cost of A$60 million (£33m) or more.
Earlier this week, Malaysia's government and Inmarsat released data used to determine the path of MH370 for examination by other experts. Families of the missing passengers hope the more open approach could help verify the plane's last location or point to any inconsistencies.
Australian authorities said the data supported the theory that the plane crashed after running out of fuel.
Along with surface searches, examination of satellite data and the undersea sonar searches, authorities have asked the United Nations' Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO) to check its system of hydrophones, designed to pick up possible nuclear tests, for any clues as to where the aircraft may have crashed.
"Both the CTBTO and institutions from our 183 Member States ... have analysed all relevant International Monitoring System data - infrasound, seismic and hydroacoustic - without finding any signal that could point to the fate of MH370," a spokesman from CTBTO said in an emailed response.