The initial results of an investigation into December's devastating Jeju Air crash in South Korea showed that while both of the plane's engines sustained bird strikes, its pilots turned off the less-damaged one just before its crash-landing.

Investigators found the Jeju Air flight crash-landed with only its badly damaged right engine on, but experts warned against drawing early conclusions.

The South Korea-led investigation into Jeju Air's fatal plane crash in December has "clear evidence" that pilots shut off the less-damaged engine after a bird strike, a source with knowledge of the probe said on Monday.