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MH370 report: Missing plane's underwater locator beacon battery had expired

Malaysia's prime minister said Sunday that the country remains committed to finding MH370, which disappeared with 239 people aboard.

The first comprehensive report into the disappearance of Malaysia Airlines Flight 370 showed that the jet's underwater locator beacon's battery had expired — but offered few other clues on the one-year anniversary of the plane's disappearance.

Malaysia's prime minister said Sunday that the country remains committed to finding MH370, which disappeared with 239 people aboard.

"The lack of answers and definitive proof — such as aircraft wreckage — has made this more difficult to bear," Najib Razak. "Malaysia remains committed to the search, and hopeful that MH370 will be found."

The Malaysian team investigating the disappearance of MH370 released a 584-page interim report on its progress on Sunday — much of which focused the ordinary nature of the flight.

There were no unusual health-related issues for the cabin crew — save for an inflight supervisor having experienced seizures — and the captain's ability to handle stress at work and home was deemed good. There were "no behavioral signs of social isolation, change in habits or interest, self-neglect, drug or alcohol abuse of the captain, first officer and cabin crew," the report added.

No unusual weather phenomena existed at the time of the flight's disappearance and its transponder was operating "satisfactorily," the report found.

However, the report revealed that the battery on the beacon attached to MH370's Flight Data Recorder had expired in December 2012 but the fact went unnoticed because of a computer data error.

While it is possible the battery will operate past the expiry date, "it is not guaranteed that it will work or that it would meet the 30-day minimum requirement," according to the report.

The significance of the expired battery on the beacon of the Flight Data Recorder was not immediately apparent, except indicating that searchers would have had lesser chance of locating the aircraft in the Indian Ocean, where it is believed to have crashed, according to The Associated Press.

The Associated Press contributed to this report.

This story originally appeared on NBC News.