There is a “decreasing possibility” of success in locating the missing Malaysia Airlines Flight MH370, the head of the Australian Transport Safety Bureau, which is leading the search for the plane, told the Guardian Tuesday. Martin Dolan's comments came days after ATSB confirmed that the last two pieces found in the western part of the Indian Ocean were almost certainly from the missing Boeing 777-200.

Dolan raised doubts over the success of the underwater search for the missing plane as about 5,790 square miles of the ocean floor is yet to be scoured before the search operation is called off in July. A multimillion-dollar search of an area of 46,332 square miles in a remote part of the southern Indian Ocean has so far yielded no concrete clues as to what might have happened to Flight MH370. The passenger plane disappeared on March 8, 2014, with 239 people on board while on its way from Kuala Lumpur to Beijing.

“When we walked into this, the best advice we had from all experts is that it was highly probably but not certain the aircraft would be found in this area. We have to contemplate now the possibility that we will not find the aircraft," Dolan told the Guardian, adding that after two years of searching, that would mean “a lot of very disappointed people."

“They’ve put their hearts and souls into something that we thought — and still think — has a high prospect of success. We’re just now contemplating the alternative," he said.

Dolan, who in March had expressed confidence that it's “very likely” that Flight MH370 will be found, stressed that hopes of finding the plane have faded. He also estimated that the search operation will conclude “mid-year,” but added that bad weather could cause delays.

Last month, Australian authorities confirmed that the two new debris pieces — a segment of Boeing 777 engine cowling and an interior panel from the main cabin — found on March 22 and March 30 on the beaches in Mossel Bay, South Africa, and Rodrigues Island in Mauritius, were "almost certainly" from the missing plane.

Last month, ATSB said that two items from Mozambique, which were found on Dec. 27, 2015, and Feb. 27, 2016, provided almost irrefutable evidence that the parts were from the missing plane.

In July 2015, a flaperon belonging to Flight MH370 turned up on the French-controlled Réunion Island in the Indian Ocean.