The Asiana Airlines Boeing 747-400F that crashed into the sea off Jeju Island on 28 July had fire in its hold, but the fire's role in the crash itself is unclear.
However, South Korea's Ministry of Land, Transport and Maritime affairs said the fire probably caused the crash.
"The exact cause (of the crash), however, still has to be determined by MLTMA after the aircraft's black box is retrieved," MLTMA said.
The aircraft was carrying 400kg of lithium batteries, paint and other potentially dangerous materials.
While there is no immediate evidence that the cargo contributed to the accident, lithium batteries are considered a potentially hazardous because they pose the risk of an in-flight fire.
A UPS 747-400F, which crashed in Dubai in September 2010, was transporting lithium batteries when the aircraft suffered a fire in cruise and attempted to divert.
The Asiana flight took off on a regular cargo service from Seoul's Incheon airport to Shanghai Pudong airport in China at 02:47 local time.
At 04:11 local time, the crew reported "control problems at an altitude of 7,600ft and was diverted to Jeju International Airport when contact was lost with the aircraft".
The aircraft's "last communication with the control center in Shanghai was that there was a fire in the cargo hold", MLTMA said.
MLTMA confirmed it had found aircraft debris floating in the sea and an orange life-vest from the aircraft.
There were two crew, a pilot and co-pilot, in the missing aircraft, MLTMA added.
The airframe was built in 2006 and has clocked 26,300h, as shown in Flightglobal's ACAS data.
The aircraft is powered by four GE CF6-80C2 engines.
Asiana operates five 747-400Fs, four 747-400BDSFs, and two 747-400 combis.