The discovery of the missing data suggests all power may have been cut, which is rare, a former government accident investigator said.

The two flight recorders on board a South Korean airliner stopped working before the jet crashed during an emergency landing and subsequent crash that killed 179 of the 181 people on board, officials said Saturday.

The missing data deepens the puzzle of what caused the deadly air disaster in Muan, South Korea, late last month.

South Korea’s leading low-cost carrier, heavy with debt and its stock already near record lows, is now facing intense public and government scrutiny.

Before it suffered the deadliest crash in South Korea's history, budget airline Jeju Air was moving fast: racking up record passenger numbers and flying its aircraft more than domestic rivals and many of its global peers,

Two people, both flight attendants, are the only survivors of the crash and are being treated at South Korean hospitals.

Ultimately, the plane crashed, killing 179 people in South Korea’s worst aviation disaster. A standard pre-flight inspection found “no issues” with the Jeju Air passenger plane before it crashed.

The two black boxes on the Boeing jet involved in the worst aviation disaster on South Korean soil stopped recording about four minutes before the accident, the transport ministry said on Saturday. South Korean investigators previously said the flight data and cockpit voice recorders were key to finding out the cause of last month's crash that killed 179 people.

The flight data and cockpit voice recorders on the Jeju Air jet that crashed on Dec. 29 stopped recording four minutes before the airliner hit a concrete structure at South Korea's Muan airport, the transport ministry said on Saturday.