Indonesia search and rescue teams hunting for the wreck of an AirAsia passenger jet have located two "big objects" in the Java Sea, agency chief Fransiskus Bambang Soelistyo told reporters on Saturday.

The two objects found just before midnight on Friday are around 30 metres (90 feet) underwater and the agency is attempting to get images using remotely operated underwater vehicles (ROV), Soelistyo told a news conference in Jakarta.

An Indonesia AirAsia Airbus A320-200 plunged into the Java Sea on Sunday while en route from Indonesia's second-biggest city Surabaya to Singapore with 162 people on board. No survivors have been found.

"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."

The first object measures 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, but that divers were preparing to search for the objects.

An official said 30 bodies had so far been recovered, some still strapped in their seatbelts, along with pieces of the broken-up plane, in the Indonesian-led search for Flight QZ8501 that is concentrated on 1,575 square nautical miles of the northern Java Sea.

Aircraft combed the sea and shoreline off Borneo on Saturday for wreckage hoping to take advantage of a brief break in bad weather that has hampered efforts to find the plane and its black box flight recorders.

Investigators hope the voice and flight data will solve the mystery of what happened to Flight QZ8501 as it flew through a severe storm over the Java Sea.

"After the black box is found, we are able to issue a preliminary report in one month," said Toos Sanitioso, an investigator with the National Committee for Transportation Safety on Friday. "We cannot yet speculate what caused the crash."

Indonesia's search and rescue agency said the search area had been widened on Saturday as debris may have drifted more than 200 nautical miles, adding helicopters would concentrate on searching the coastline of southern Borneo.

Shallow seas

The cause of the crash, the first suffered by the AirAsia group since the budget operator began flying in 2002, is unexplained. Investigators are working on a theory that the plane stalled as it climbed steeply to avoid a storm about 40 minutes into a flight that should have lasted two hours.

The plane was flying at 32,000 ft (9,753 metres) and the pilot had asked to climb to 38,000 ft to avoid bad weather just before contact was lost. When air traffic controllers granted permission to fly at 34,000 ft a few minutes later, they got 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.

Weather reports

Hadi Mustofa Djuraid, a Transport Ministry official, told reporters on Friday that authorities were 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.

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, 49 percent owned by Malaysia-based AirAsia.

Indonesia's transport ministry said late on Friday it had temporarily suspended Indonesia AirAsia's Surabaya-Singapore flight because it had apparently operated the service beyond the duration of its licence.

"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.

Three airline disasters involving Malaysian-affiliated planes in under a year have spooked travellers.

Malaysia Airlines Flight MH370 disappeared in March en route from Kuala Lumpur to Beijing with 239 passengers and crew and has not been found. On July 17, the same airline's Flight MH17 was shot down over Ukraine, killing all 298 people on board.

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