Investigators looking for a Malaysia Airlines plane that crashed in 2014 said Tuesday they have concluded with a "high degree of confidence" that the aircraft is not in a massive area of the Indian Ocean where they have been conducting their search.

The probe has cost about $150 million and covered 120,000 square kilometers without finding a trace of the wreckage. Some 20 piece of debris likely to have come from the plane have washed up on shores along the western Indian Ocean.

A report from the Australian Transport Safety Bureau, which is leading the investigation, said that after analyzing satellite data and aircraft debris drift modeling they believe the area with the highest probability of containing the plane is just north of the previous search zone.

The report said if that 25,000 kilometer section is searched, then the investigators will have exhausted possible areas for finding the plane.

The current search mission is due to end next month.

"As agreed at the Tripartite Ministers meeting in Malaysia in July, we will be suspending the search unless credible evidence is available that identifies the specific location of the aircraft," Australian Transport Minister Darren Chester said in a statement Tuesday.

Chester said he remains hopeful the plane will be found.

Malaysia Airlines Flight MH370 was flying from Beijing to Kuala Lumpur in March 2014 when it disappeared with 239 people on board.