SYDNEY (BLOOMBERG) - The chances of finding missing Malaysia Airlines Flight MH370 are fading and searchers have to face possible failure, the head of the Australian investigation team told the Guardian newspaper.

With about 15,000 sq km left to scour of a 120,000 sq km search area in the southern Indian Ocean, there's a "decreasing possibility" of success, Martin Dolan, head of the Australian Transport Safety Bureau, said in an interview, the Guardian reported Tuesday (May 17).

When Dolan's group began the search, the best advice received by experts was that it was highly probable, "but not certain the aircraft would be found in this area," Dolan said, according to the newspaper.

"We have to contemplate now the possibility that we will not find the aircraft."

Dolan was more upbeat in an interview in February, when he said he was still confident of finding the wreckage.

The Boeing 777 plane vanished from radar on March 8, 2014, en route to Beijing from Kuala Lumpur. There has been no trace of the 239 people on board.

Bad weather may delay the completion of the search - originally slated for the middle of the year - by at least a month, Dolan told the newspaper.

The Australian Transport Safety Bureau said this month that a piece of engine cowling and an interior cabin panel, found separately in March in South Africa and Mauritius, were "almost certainly" from MH370.

Those locations match the flow of currents from the existing search zone, the bureau said.