Indonesian divers believe they are close to finding the cockpit voice recorder of a Sriwijaya Air jet that plunged into the sea shortly after takeoff with 62 people onboard.

Divers retrieved the plane's flight data recorder (FDR) from the seabed on Tuesday and officials said they had also found the beacon that was attached to the cockpit voice recorder (CVR). "God willing, we will find it today," said Navy official Wahyudin Arif, referring to the cockpit voice recorder.

Indonesia team search and rescue bring debris from Sriwijaya aircraft that crash on Wednesday in Jakarta, Indonesia. Photo: VCG

He told KompasTV on Wednesday divers would comb a very narrow area of the seabed for the voice recorder, adding that divers found the first black box by shifting debris on the seabed piece by piece and he suspected the same process would be needed to find the other recorder.

Military chief Hadi Tjahjanto said on Tuesday he had "high confidence" of finding the recorder soon.

The Boeing 737-500 jet crashed into the Java Sea on Saturday four minutes after takeoff from Jakarta's main airport.

Investigators will rely heavily on the two black boxes to determine the cause of the crash.

Indonesia's National Transportation Safety Committee expects to download the FDR data within two to five days.