Divers prepare their gear on the deck of the Search and Rescue (SAR) ship KN Purworejo during a search operation for passengers onboard AirAsia Flight QZ8501 in the Java Sea January 4, 2015. [Photo/Agencies]

The latter effort is focused on an area about 90 nautical miles off Borneo, where ships using sonar have located five large objects believed to be parts of the plane - the largest about 18 metres (59 feet) long - in shallow water.

The captain of an Indonesian navy patrol vessel said on Monday his ship had found what was believed to be the tail - a key find since that section of the aircraft houses the cockpit voice and flight data recorders - but Soelistyo said that could not be confirmed.

Only 37 bodies of the mostly Indonesian passengers and crew have been recovered. Many more could still be trapped in the fuselage of the aircraft.

"Why are we trying to search the big parts of wreckage? Because there might be the possibility that there are still victims in the body of the plane," said Soelistyo.

Some divers were in action, and five ships were scouring the sea floor with acoustic "pinger" detectors designed to pick up signals emitted by the black box, he said.

AVIATION CRACKDOWN

The crash was the first fatal accident suffered by the AirAsia budget group, whose Indonesian affiliate has come under criticism from the authorities in Jakarta since the disaster.

The transport ministry has suspended Indonesia AirAsia's Surabaya-Singapore licence, saying the carrier only had permission to fly the route on Mondays, Tuesdays, Thursdays and Saturdays. Flight QZ8501 took off on a Sunday.