The underwater search for the missing Malaysia Airlines jet is to be expanded, Australia's prime minister has said.
Tony Abbott said the US Navy's Bluefin 21 mini-sub had finished scouring the initial search area far off the Australian west coast and had not yet found anything.
"It is now 52 days since Malaysia Airlines Fight MH370 disappeared and I'm here to inform you that the search will be entering a new phase," Mr Abbott told a news conference.
Radar and satellite data show the jet carrying 239 passengers and crew veered far off course on March 8 for unknown reasons during a flight from Kuala Lumpur 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 recovered since the massive multi-national hunt began.
The Bluefin's original search area was a circle with a six-mile radius 2.8 miles deep around a spot where signals consistent with a plane's black boxes were heard on April 8.
"I want the families to know, I want the world to know, that Australia will not shirk its responsibilities in this area. We will do everything we humanly can ... to solve this mystery," Mr Abbott said.
"We will not let people down and while the search will be moving to a new phase in coming weeks, it certainly is not ending."
Australian head of the search effort Angus Houston, said: "We haven't found anything anywhere that has any connection to MH370."
Crews will now begin searching the plane's entire probable impact zone, an area 430 miles long and 50 miles wide.
That will be a monumental task - and one that will take time, retired air chief marshal Mr Houston warned.
"If everything goes perfectly, I would say we'll be doing well if we do it in eight months," he said, adding that weather and technical issues could cause the search to drag on well beyond that estimate.
Australian officials will be contacting private companies to bring in additional sonar mapping equipment that can be towed behind boats to search the expanded area at an estimated cost of 60 million dollars Mr Abbott said.
It could take officials several weeks to organise contracts for the new equipment and in the meantime, the Bluefin will continue to scour the sea bed.
So far, each country involved in the search has been bearing its own costs. But Mr Abbott said Australia would now seek contributions from other countries to help pay for the cost of renting the new equipment.
Despite the Bluefin's failure to find any wreckage, the prime minister said he has a "considerable degree of confidence" that the underwater signals picked up by sound-detecting equipment on April 8 were from the plane's black boxes.
"We're still baffled and disappointed that we haven't been able to find undersea wreckage based on those detections, and this is one of the reasons why we are continuing to deploy the Bluefin 21 submersible - because this is the best information that we've got," he said.