A Delta Air Lines jet heading for Narita International Airport on Wednesday declared an in-flight emergency after an apparent engine failure over a remote part of the ocean, the airline said Thursday.

Flight DL275 from Detroit was over the Bering Sea when a sensor indicated a fault in one of its engines and the pilot shut it down. The Boeing 747-400 had 332 people aboard.

"The captain declared an emergency," Delta spokesman Masaji Takahashi told The Japan Times. "This was precautionary, and nothing happened. Eventually it safely arrived at Narita."

Takahashi said an indicator in the cockpit showed oil consumption had declined in the No. 2 engine. He said the jet, which has four engines, had sufficient remaining power to continue its flight.

There was no confirmation whether passengers were informed about the alarm. Takahashi said when a plane declares an emergency it secures priority landing at an airport.

At the time of the incident, the plane was 260 km to the north of Attu Island, Alaska, far from any possible landing site, reported industry news agency The Aviation Herald.

It descended and flew at a lower altitude for the rest of its journey, online flight tracking data showed.

A display of the plane's path recorded by the flight monitoring service flightaware.com appeared to show it deviating from its track to hug the coast of Russia as it approached Japan.