Authorities have suggested that migratory bird strikes were the cause of last month's deadly plane crash in South Korea, according to multiple reports.

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

The exact cause of the Jeju Air crash remains unclear, and the investigation is complicated because the black boxes stopped recording four minutes before impact.

South Korean officials investigating the fatal Jeju Air crash have published a preliminary report of the accident.

Both engines of the Jeju Air plane that crashed last month contained duck remains, according to a preliminary report on Monday, with authorities still trying to determine what caused the deadliest air disaster on South Korean soil. Julian Satterthwaite reports.

Seoul: The South Korean transport ministry on Saturday has revealed that the ill-fated Jeju Air flight, involved in last month’s deadly crash, received a warning from air traffic control about potential bird activity just one minute before its black box recording stopped.

The first report on last month’s Jeju Air crash in South Korea confirmed bird strikes in the plane's engines, though officials haven't determined

The first report on last month’s Jeju Air crash in South Korea confirmed traces of bird strikes in the plane's engines, though officials haven’t determined the cause of the accident that killed all but two of the 181 people on board.

The report also said the plane's two black boxes — the flight data recorder and cockpit voice recorder — stopped recording about 4 minutes before the crash.