South Korean officials are launching an investigation into the cause of the fire that engulfed an Air Busan passenger plane, with eyewitness accounts suggesting a power bank may have sparked the blaze.

South Korea’s authorities investigating last month’s Jeju Air plane crash have submitted a preliminary accident report to the UN aviation agency and to the authorities of the United States, France and Thailand,

Pilots’ actions after the bird strike are an early focus of the investigation, according to people familiar with the probe.