BEIJING — The battery on one of two underwater beacons attached to the flight data and cockpit voice recorders of missing Malaysia Airline Flight 370 expired more than a year before the plane vanished, the Malaysian government said Sunday in an interim report issued on the anniversary of the disappearance.

That finding suggests that searchers listening for “pings” from the beacons on the recorders after the Boeing 777 went missing last March 8 with 239 people aboard may have never had a chance of detecting a signal from one of the devices.

No wreckage from the plane has been found. Sonar-equipped boats continue to search for the aircraft more than 1,000 miles off the west coast of Australia.

The report issued Sunday, which is required under international aviation agreements, offered few new insights into the cause of the plane’s disappearance. Even the battery issue, while perhaps pertinent to the question of why it has been so difficult to locate the missing Boeing 777, does not bear on why the jet vanished.

The report indicates neither the pilot, first officer nor crew exhibited signs of personal or financial stress, medical problems or substance abuse that might suggest a motive for foul play.

Investigators reviewed closed-circuit video of Capt. Zaharie Ahmed Shah on the day of the flight and three earlier flights and observed “no significant behavioral changes” or unusual mannerisms. They said Shah had three bank accounts and three cars and two houses and examination of his spending “indicated nothing unusual.”

Kok Soo Chon, who led the investigation, told Malaysia’s official Bernama news agency that the sole objective of the investigation was to prevent future accidents or incidents, not to assign blame or liability.

More than 150 of the passengers aboard the flight, which was bound from Kuala Lumpur to Beijing, were Chinese citizens.

China’s foreign minister, Wang Yi, said Sunday that the search for MH370 would not stop. “The search for MH370 will continue,” Wang said on the sidelines of the annual meeting of China’s legislature.

Sunday’s report made no significant comment on the beacon battery lapse, but said the battery was not replaced on time because of a computer system used to track and call out maintenance issues had not been updated properly.

The battery on the beacon of the flight data recorder expired in December 2012, the report said. Such beacons are supposed to function for 30 days in water up to 20,000 feet deep after a crash to help searchers find the device.

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