DHAKA: Australian Prime Minister Tony Abbott has announced the search for missing Malaysia Airlines flight MH370 is entering a new phase, focusing on a larger underwater area.

Abbott says it has been 52 days since the plane disappeared and it is now highly unlikely that any debris will be located on the ocean surface, reports the abc.net.au.

"By this stage, 52 days into the search, most material would have become water logged and sunk," he told reporters in Canberra.

"With the distances involved, all of the aircraft are operating at close to the limit of sensible and safe operation.

"Therefore, we are moving from the current phase to a phase which is focused on searching the ocean floor over a much larger area."

Abbott says Australia will continue to do what it can to answer the mystery of what happened to MH370.

"While the search will be moving to a new phase in coming weeks, it certainly is not ending," he said.

The Boeing 777, which was carrying 239 people, including six Australians, vanished on March 8.

Since then a massive multinational aerial and sea search effort has been underway.

The Prime Minister, who addressed reporters alongside search co-ordinator retired Air Chief Marshal Angus Houston, says the search's new phase, which will include commercial contractors, will cost "in the order of $60 million".

"Up [until] now, every nation has been bearing its own costs and, in the case of Australia, we have been essentially using Australian military assets, assets we would be paying for anyway," he said.

"No-one should underestimate the degree of responsibility that Australia has here, because this has happened in our search and rescue zone, and there were, after all, six Australia citizens and one Australian resident on that aircraft.

"We will be seeking some appropriate contributions from other nations involved, but we will ensure that this search goes ahead." 

BDST:1040 HRS, APR 28, 2014