SYDNEY (CNN) — The underwater search for missing Malaysia Airlines Flight 370 could come to an end in the first half of next year.

Search teams have been combing a vast area of the seafloor in a remote part of the southern Indian Ocean, hunting for traces of the passenger jet and the 239 people it was carrying.

The search zone, where officials believe the Boeing 777 is most likely to have ended up, was expanded earlier this year from 60,000 square kilometers to 120,000 kilometers, bigger than the U.S. state of Pennsylvania.

Australia, which is leading the underwater hunt, announced Wednesday that the zone is unlikely to get any bigger.

“In the absence of credible new information that leads to the identification of a specific location of the aircraft, gvernments have agreed that there will be no further expansion of the search area,” the Australian agency coordinating the search said in a statement.

The other two countries involved in the search are Malaysia, where Flight 370 began its journey, and China, where most of the passengers were from.

When the governments announced plans to increase the search zone to 120,000 square kilometers in April, they said it could take roughly another year.

Australian authorities said Wednesday that more than 50,000 square kilometers have been covered so far.

Flight 370 disappeared after taking off from Kuala Lumpur, Malaysia, on March 8, 2014, bound for Beijing.

Authorities still don’t know why it turned dramatically off course over the sea between Malaysia and Vietnam, or where exactly its errant journey finished.

Family members of the people on board say they have been left in limbo, with the absence of tangible evidence feeding hopes that their loved ones are still alive.

An international team of experts used satellite data to calculate that the plane eventually went down in the southern Indian Ocean, far off the coast of Western Australia.

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