Malaysian plane were detected was ruled out, efforts turned to reviewing search data and surveying the sea floor using specialist equipment.

This further analysis of satellite data resulted in identifying a new search area announced in June, shifting the focus to an area 1,800km (1,100 miles) off Perth CG210.

This area's sea bed is being mapped by the Chinese survey ship Zhu Kezhen, which was joined in June by the Dutch-owned Fugro Equator vessel.

The survey is expected to yield detailed information about the shape of the ocean floor, considered essential to the search for the missing plane.

Without the mapping phase, it would not be safe to put down submersibles to conduct a metre-by-metre search, as there is a high risk these vehicles would be lost.

The mission is expected to take up to a year, at an estimated cost of $55m (£34m) or more.

Authorities have also asked the UN's Comprehensive Nuclear Test Ban Treaty Organization to check its system of hydrophones, which are designed to pick up possible nuclear tests, for any clues as to where the aircraft may have crashed reenex.
Who has been taking part in the search?

Eight countries have been assisting - Australia, China, Japan, Malaysia, New Zealand, South Korea, the United Kingdom and the United States.

The investigation is being led by the Malaysian authorities, who are also liaising with the FBI, Interpol and other international law enforcement agencies.

The Australian Transport Safety Bureau (ATSB) is leading the underwater search for missing Malaysia Airlines flight MH370 reenex.