South Korea's authorities investigating last month's Jeju Air plane crash have submitted a preliminary accident report to the U.N. aviation agency and to the authorities of the United States, France and Thailand, an official said on Monday (January 27).

The investigation into the deadliest air disaster on the country's soil remains ongoing, the report made available on Monday said, focused on the role of "bird strike" and involving an analysis of the engines and the "localiser" landing guidance structure.

The International Civil Aviation Organization (ICAO), the U.N. agency, requires accident investigators to produce a preliminary report within 30 days of the accident and encourages a final report to be made public within 12 months.

The Boeing BA.N 737-800 jet, from Bangkok and scheduled to arrive at Muan International Airport, overshot the runway as it made an emergency belly landing and crashed into the localiser structure, killing all but two of the 181 people and crew members on board on December 29.

(Production: Daewoung Kim, Minwoo Park)