Indonesian divers on Thursday found the flight data recorder of a Lion Air aircraft that crashed into the Java Sea earlier this week with 189 people on board, officials said.

"This is most likely the FDR [flight data recorder]," said Bambang Irawan, an investigator from the National Transport Safety Committee. "We're still looking for the CVR [cockpit voice recorder]." 

The CVR records conversations in the cockpit, while the FDR tracks flight data such as airspeed, pressure altitude and vertical acceleration. Data from the recorders could shed light on the cause of the crash.

Transport Minister Budi Karya Sumadi said the National Transportation Safety Committee would analyse data from the black box and that its investigation would be "professional and impartial."  

A naval diver who retrieved the device from a depth of 30 metres on the seabed said it was still intact.

Search and rescue chief Muhammad Syaugi said navy divers also found an object - measuring about 1.5 metres - believed to be a piece of the aircraft. 

Military commander Air Chief Marshal Hadi Tjahjanto said late Wednesday that he believed the aircraft's fuselage was "not far from the area" where ping signals from the black box were detected.

The Boeing 737 MAX 8 plunged into the sea about 13 minutes after take-off from Jakarta's Soekarno-Hatta International Airport, killing all 181 passengers and eight crew members. 

Search chief Muhammad Syaugi said the discovery of items including clothes and in-flight magazines on the seabed indicated that the fuselage was nearby and that many bodies may be still trapped there.

He said the fuselage would be lifted using a crane once it was found.

Syaugi said 57 bags of human remains have been collected so far, however only one victim has been identified so far, according to police.   

The aircraft was bound for Pangkal Pinang in the province of Bangka-Belitung Islands when it crashed. 

Lion Air has confirmed reports that the aircraft logged "unreliable" readings of altitude and airspeed on its previous flight, the night before it crashed.

But the company said the issues had been resolved before Monday's flight. 

Monday's crash was the second deadly accident involving a Lion Air plane in 14 years. 

In 2004 the airline's McDonnell Douglas MD-82 overshot the runway of the airport in the central Java city of Solo and crashed onto a cemetery, killing 25 people. 

In 2013, a Lion Air Boeing 737 carrying more than 100 people crashed into the sea while trying to land on the resort island of Bali, nearly splitting the fuselage in two, though there were no fatalities. 

Indonesia, the world's largest archipelagic country, has experienced a boom in low cost-carriers following the liberalization of the aviation industry in the early 2000s.  

In June, the European Union lifted a ban of Indonesian airlines from its list of carriers, which was imposed in 2007 following a string of deadly air incidents. 

Several of the Indonesian airlines, including flag carrier Garuda, were taken off the ban list in 2009 after steps were taken to improve safety.

Last year, the International Civil Aviation Organization ranked Indonesia's aviation safety as above global average, with a compliance rate of 81.15 per cent.