Ships searching for the wreck of an AirAsia passenger jet that crashed with 162 people on board have pinpointed two "big objects" on the sea floor, the head of Indonesia's search and rescue agency said on Saturday.

The breakthrough came as authorities in Jakarta said that Indonesia AirAsia was violating the terms of its licence for the Surabaya to Singapore route by flying on a Sunday, the day the Airbus  A320-200 plunged into the Java Sea, and said they would investigate the budget carrier's other schedules.

Search and rescue agency chief Fransiskus Bambang Soelistyo said underwater remote operating vehicles (ROV) were being used to try to capture images to confirm the underwater objects were parts of the lost plane.

"We have detected two objects underwater (at) 30 metres depth," said Soelistyo. "At this moment we are operating the ROV to take pictures of the objects."

A multi-national task force of ships, planes and helicopters have been scouring the northern Java Sea and coastline of southern Borneo to recover the bodies of victims and locate the wreck of Flight QZ8501 and its black box flight recorders.

No survivors have been found from the crash, which happened about 40 minutes after the plane took off from Indonesia's second largest city in an area known for intense tropical thunderstorms during the current monsoon season.

Air traffic controllers lost contact with Flight QZ8501 minutes after the pilot requested to fly higher to try and avoid a storm cell.

Indonesian authorities on Friday questioned whether the pilot had followed correct weather report procedures, and later suspended Indonesia AirAsia's Surabaya to Singapore flights for apparently infringing the terms of its licence for the route.

Djoko Murdjatmodjo, acting director general of air transportation, said on Saturday that the transport ministry would investigate all AirAsia schedules from Monday.

"We are going to investigate all AirAsia flight schedules. Hopefully we can start on next Monday. We won't focus on licences, just schedules," he said. "It is possible AirAsia's license in Indonesia might be revoked," he added, stressing that was only one possibility.

Sunu Widyatmoko, Indonesia AirAsia chief, told reporters the airline would cooperate with the inquiry.

"The government has suspended our flights from Surabaya to Singapore and back," he said. "They are doing the evaluation process. AirAsia will cooperate fully with the evaluation."

RECOVERING VICTIMS

Much of the effort has focussed on finding victims of the crash. Officials said 21 bodies were pulled from the sea on Friday, including two still strapped in their seats, bringing the total number of victims recovered to 30.

Small pieces of the aircraft and other debris have also been found, but there has been no sign of the crucial voice and flight data recorders - the so-called black boxes that investigators hope will unravel the sequence of events in the cockpit during the doomed jet's final minutes.

Search and rescue agency chief Soelistyo told a news conference in Jakarta that two large objects were found just before midnight on Friday.

The first object measured 9.4 metres by 4.8 metres by 0.4 metres (30 feet by 15 feet by 1.3 feet), while the second is 7.2 metres by 0.5 metres (24 feet by 1.6 feet), he said.

Soelistyo said operating ROVs was problematic due to the large waves in the area that have hampered operations for much of the week, but that divers were preparing to search for the objects.

The cause of the crash, the first suffered by the AirAsia  group since the budget operator began flying in 2002, is unexplained.

The plane was flying at 32,000 ft (9,753 metres) and the pilot had asked to climb to 38,000 ft just before contact was lost. When air traffic controllers granted permission to fly at 34,000 ft a few minutes later there was no response.

A source close to the investigation said radar data appeared to show the aircraft made an "unbelievably" steep climb before it crashed, possibly pushing it beyond the A320's limits.

LICENCE SUSPENDED

Indonesia's transport ministry said late on Friday that the terms of Indonesia AirAsia's licence for the Surabaya-Singapore route permitted flights on four days of the week but not Sundays.

"As of Jan. 2, 2015, the licence of Surabaya-Singapore (return) route to Indonesia AirAsia is temporarily frozen until after there is a result of evaluation and investigation," said spokesman Julius Adravida Barata.

Hadi Mustofa Djuraid, a transport ministry official, told reporters on Friday that authorities were also investigating the possibility that the pilot did not ask for a weather report from the meteorological agency at the time of take-off.

Indonesia AirAsia said in a statement that weather reports were printed in hard copy at the operations control centre at all its flight hubs, including Surabaya, and taken by the pilot to the aircraft before each flight.

An AirAsia spokeswoman declined to comment on whether the pilot had followed the procedure described in the statement.

The Indonesian captain, a former air force fighter pilot, had 6,100 flying hours on the A320 and the plane last underwent maintenance in mid-November, according to Indonesia AirAsia.

On board Flight QZ8501 were 155 Indonesians, three South Koreans, and one person each from Singapore, Malaysia and Britain. The co-pilot was French.