"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 Joint Agency Co-ordination Centre (JACC) said on Thursday.

Yesterday afternoon Bluefin-21,  a Towed Pinger Locator deployed from Australian Defence Force vessel Ocean Shield, completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April.

"The data collected on yesterday’s mission has been analysed. As a result, the JACC can advise that no signs of aircraft debris have been found by the autonomous underwater vehicle since it joined the search effort."

Ocean Shield departed the search area last night and is expected to arrive at Fleet Base West on Saturday.

Malaysia Airlines MH370 went missing on March 8, on a night flight from Kuala Lumpur to Beijing.

JACC announced on April 7 that a pinger locator towed from the Australian navy vessel Ocean Shield had picked up two acoustic signals in the Indian Ocean, one of which it held for more than two hours.

At the time, the signals were described as as consistent with flight data or cockpit voice recorders and Prime Minister Tony Abott said they were the most promising lead yet in the search to MH370.

Since Bluefin-21 has been involved in the search, it has scoured over 850 square kilometres of the ocean floor looking for signs of the missing aircraft.

The JACC said the search for MH370 will continues and now involves three major stages:

  - Reviewing all existing information and analysis to define a search zone of up to 60,000 square kilometres along the arc in the southern Indian Ocean;

  - Conducting a bathymetric survey to map the sea floor in the defined search area; and

  - Acquiring the specialist services required for a comprehensive search of the sea floor in that area.

An expert satellite working group continues to review and refine radar and satellite data and aircraft performance data to determine where the aircraft most likely entered the water. The findings of the review will be made public in due course.

The Chinese survey ship Zhu Kezhen has  begun conducting a bathymetric survey to map the ocean floor in areas provided by the ATSB.

Its operations are being supported by the Chinese ship Haixun 01 and Malaysian vessel Bunga Mas 6 which are assisting with transporting the survey data to Fremantle weekly for further processing by Geoscience Australia. A contracted survey vessel will join the Zhu Kezhen in June.

The bathymetric survey is expected to take about three months. Knowing the seafloor terrain is crucial to enabling the subsequent underwater search.

The underwater search will aim to locate the aircraft and any evidence (such as aircraft debris and flight recorders) to assist with the Malaysian investigation of the disappearance of MH370.

It is anticipated that this component of the search will begin in August and take up to 12 months.

The ATSB will shortly release a formal request for tender to source the capability to undertake the underwater search.

A single prime contractor will be chosen to bring together and manage the expertise, equipment and vessels to carry out the search.

The request for tender will be done via AusTender, the Australian Government Tender System at www.tenders.gov.au.