SYDNEY - Australia began the process of finding a private contractor on Wednesday to take over the hunt for a missing Malaysia Airlines plane after three months of military-led searches failed to find any trace of its wreckage.
The Boeing 777, carrying 239 passengers and crew, disappeared from radar screens on March 8 shortly after taking off from Kuala Lumpur bound for Beijing.
Investigators say what little evidence they have to work with suggests the aeroplane was deliberately diverted thousands of kilometres from its scheduled route before eventually crashing into the Indian Ocean.
The next phase of the search mission is expected to start in August and take up to a year, covering some 60,000 sq kilometres of ocean at a cost of A$60 million ($55.5 million) or more. The search is already the most expensive in aviation history.
"A single prime contractor will be chosen to bring together and manage the expertise, equipment and vessels to carry out the search," Australia's Joint Agency Coordinating Centre, which has been leading the multinational search, said in a statement.
The search was narrowed in April after a series of acoustic pings thought to be from the plane's black box recorders were heard near where analysis of satellite data put its last location, some 1,600 km (1,000 miles) off the northwest coast of Australia.
But officials said last week wreckage from the aircraft was not in the area they had identified and that the search would be expanded.
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.
However, the CTBTO last week ruled out any of their data pointing to the crash.
On Wednesday, researchers at Australia's Curtin University also poured cold water on a potentially promising noise detected by sensors off Australia's coast around the time of the crash.
"I'd like to think it's something related to the aircraft, but I think it's more likely that it is a small underwater seismic event," Dr Alec Duncan, Senior Research Fellow at the university's Centre for Marine Science and Technology, told reporters.