Indonesian Navy divers have recovered one of the two black boxes from AirAsia flight QZ8501 in the Java Sea.

The divers have also located the cockpit voice recorder around 20m away from the flight-data recorder, but it has yet to be recovered.

Halfway on its two-hour flight from Indonesia’s Surabaya to Singapore, the AirAsia A320-200 ran into trouble and lost contact with the air traffic control before it crashed flying over the Java Sea.

So far, 48 bodies of passengers and crew have been recovered and those missing could be trapped inside the aircraft.

"The flight-data recorder will be analysed at an air-crash investigation laboratory in Jakarta."

Indonesia search-and-rescue agency head Fransiskus Bambang Soelistyo was quoted by Reuters as saying: "We succeeded in lifting the part of the black box known as the flight data recorder.

"We are still trying to find the cockpit voice recorder."

The flight-data recorder will be analysed at an air-crash investigation laboratory in Jakarta.

If the devices are not damaged, the black box recorders will help investigators identify the cause of the crash.

Investigators said that it could take up to two weeks to download data from the devices.

The Indonesia weather bureau said that seasonal storms could be a possible factor for the crash.

Indonesia national search-and-rescue agency operations coordinator Suyadi Bambang Supriyadi told Reuters that the sonar had detected an object measuring 10m by 4m by 2.5m on the sea floor.

Supriyadi said: "They suspect it is the body of the plane.

"If it is the body of the plane, then we will first evacuate the victims."

Last week, the tail section of the aircraft was raised from the sea using inflatable balloons and loaded onto a vessel.