An Airbus investigator walks near part of the tail of the AirAsia QZ8501 passenger plane in Kumai Port, near Pangkalan Bun, Central Kalimantan January 12, 2015. Photo: Reuters

Indonesian divers have retrieved the flight data recorder of crashed AirAsia Flight QZ8501, say officials.

The head of Indonesia's search and rescue agency, Bambang Soelistyo, said teams were still looking for the second device, its cockpit voice recorder.

AirAsia flight QZ8501 disappeared in bad weather on 28 December with 162 people on board.

The aircraft, which was flying from Surabaya in Indonesia to Singapore, is thought to be deep in the Java Sea.

Dozens of bodies have been recovered but most of the victims are believed to still be inside the fuselage, which has not been found.

It is hoped that the recovery of the flight data recorder will help investigators find out what happened to the plane during what should have been a brief, routine flight.

Indonesian police remove tarpaulin from part of the tail of the AirAsia QZ8501 passenger plane in Kumai Port, near Pangkalan Bun, Central Kalimantan January 12, 2015. Photo: Reuters

Speaking in Jakarta, Bambang Soelistyo told reporters: "I received information from the National Transport Safety Committee chief that at 07:11 (00:11 GMT), we succeeded in bringing up part of the black box that we call the flight data recorder."

"What we are still trying to find is the cockpit voice recorder."

Flight data recorders are usually housed inside the rear part of the plane.

They are designed to survive a crash and being submerged in water, and contain underwater locator beacons which emit so-called "pings" for at least 30 days.

Over the weekend, the tail section of the Airbus A320-200 was brought to the surface, but the flight recorder was not inside it, as had been hoped.

The BBC's Karishma Vaswani in Jakarta says that as long as the device is undamaged and intact, it will provide key information including the altitude at which the plane was flying and whether it stalled or encountered a mechanical failure in the moments before it crashed.

Officials said the recorder would now be taken to Jakarta for analysis, which could take up to two weeks.

The international search for the fuselage and the remaining missing passengers and crew is continuing in the Java Sea.

Mr Soelistyo said all ships now "will be deployed with the main task of searching for bodies that are still or suspected to still be trapped underwater".