Australia's Prime Minister Tony Abbott said on Monday it was now highly unlikely that any debris from the missing Malaysian jet would be found on the ocean surface, with the search effort entering a new phase.
"I am now required to say to you that it is highly unlikely that we will find any aircraft debris on the ocean surface. By this stage, 52 days into the search, most material would have become waterlogged and sunk," Abbott said at a news conference in Canberra, the Australian capital.
Malaysian Airlines Flight MH370 with 239 passengers and crew on board went missing on March 8 during a flight from Kuala Lumpur to Beijing.
It is suspected to have gone down in the southern Indian Ocean and this is where the search effort coordinated by Australian authorities in recent weeks has focused its attention.
"We are going to enter a new phase of the search, focusing under the sea. The Bluefin 21 submersible will continue in operation, we are looking to an intensified, underwater search involving different technology," Abbott added, referring to a sonar search for the plane.
"In particular, using specialized side-scan sonar equipment tied behind chips to scan the sea bed for evidence of aircraft wreckage. The Australian government, in consultation with Malaysia's government, is willing to engage 1 or more commercial companies to undertake this work," Abbott said.
Malaysia, China, Japan, New Zealand, South Korea, Britain and the U.S. are assisting Australia in trying to solve what is the most expensive search in aviation history.
Read More Timeline of Flight MH370
The cost of the operation could be in the region of A$60 million (US$ 56 billion) Abbott said at the news conference.
U.S. President Barack Obama during a visit to Kuala Lumpur, Malaysia's capital city, on Sunday said the U.S. was fully committed to providing more resources in the search for the missing plane.
Australia and Malaysia have been under pressure to bring closure to grieving families of those on board MH370, most of whom were Chinese.
"I'm not in the business of making excuses for failures, I'm in the business of doing everything we can to achieve rock solid information on the whereabouts of this aircraft," Abbott said.
"We are going to methodically, carefully, to the very best of contemporary technology, search the entire probable impact zone, 700 kilometers by 80 kilometers, we will search it all," he added.