Unidentified material that washed ashore in southwestern Australia that was examined for any link to the lost Malaysian plane is not from the jet, officials said Thursday morning local time.

The Australian Transport Safety Bureau said that after examining detailed photographs of the material, 10 kilometres east of Augusta in Western Australia state, it is satisfied it is not related to the search for missing Flight MH370.    

Augusta is near Australia's southwestern tip, about 310 kilometres from Perth, where the search operation has been based.

Meanwhile, Australia's prime minister said Wednesday that failure to find any clue in the most likely crash site of the lost jet would not spell the end of the search, as officials plan soon to bring in more powerful sonar equipment that can delve deeper beneath the Indian Ocean.

The search co-ordination centre said a robotic submarine, the U.S. Navy's Bluefin 21, had scanned more than 80 per cent of the 310-square-kilometre seabed search zone off the Australian west coast, creating a three-dimensional sonar map of the ocean floor. Nothing of interest had been found.

The 4.5-kilometre deep search area is a circle 20 kilometres wide around an area where sonar equipment picked up a signal on April 8 consistent with a plane's black boxes. But the batteries powering those signals are now dead.

Subs similar to those that found Titanic

Defence Minister David Johnston said Australia was consulting with Malaysia, China and the United States on the next phase of the search for the plane, which disappeared March 8. Details on the next phase are likely to be announced next week.

Johnston said more powerful towed side-scan commercial sonar equipment would probably be deployed, similar to the remote-controlled subs that found RMS Titanic 3,800 metres under the Atlantic Ocean in 1985 and the Australian Second World War wreck HMAS Sydney in the Indian Ocean off the Australian coast, north of the current search area, in 2008.

"The next phase, I think, is that we step up with potentially a more powerful, more capable side-scan sonar to do deeper water," Johnston told The Associated Press.

Malaysia Airlines flight MH370

A father whose son was aboard Malaysia Airlines flight MH370 asks a question during a briefing given by Malaysian representatives in Beijing. (Jason Lee/Reuters)

While the Bluefin had less than one-fifth of the seabed search area to complete, Johnston estimated that task would take another two weeks.

Australian Prime Minister Tony Abbott said the airliner's probable impact zone was 700 kilometres long and 80 kilometres wide. A new search strategy would be adopted if nothing was found in the current seabed search zone.

"If at the end of that period we find nothing, we are not going to abandon the search, we may well rethink the search, but we will not rest until we have done everything we can to solve this mystery," Abbott told reporters.

"We owe it to the families of the 239 people on board, we owe it to the hundreds of millions — indeed billions — of people who travel by air to try to get to the bottom of this. The only way we can get to the bottom of this is to keep searching the probable impact zone until we find something or until we have searched it as thoroughly as human ingenuity allows at this time," he said.

'We're flying blind'

The focus of the next search phase will be decided by continuing analysis of information including flight data and sound detections of the suspected beacons, Johnston said.

"A lot of this seabed has not even been hydrographically surveyed before — some of it has — but we're flying blind," he said, adding that the seabed in the vicinity of the search was up to seven kilometres deep.

The search centre said an air search involving 10 planes was suspended for a second day because of heavy seas and poor visibility.

But 12 ships would join Wednesday's search of an expanse covering 38,000 square kilometres, centred 1,600 kilometres northwest of Perth.

Radar and satellite data show the jet carrying 239 passengers and crew veered far off course on March 8 for unknown reasons during its flight from Kuala Lumpur, Malaysia, to Beijing. Analysis indicates it would have run out of fuel in the remote section of ocean where the search has been focused. Not one piece of debris has been found since the massive multinational hunt began.