Indonesian searchers have promised an “all-out effort” to locate bodies from AirAsia Flight QZ8501 as international investigators joined the hunt for the ill-fated plane.

Seven bodies have so far been retrieved in the search for the Airbus A320-200, which crashed into the Java Sea with 162 people on board during a storm Sunday en route from Indonesia’s second city of Surabaya to Singapore.

Two of the dead – one male and one female – have been identified and will be handed over to relatives after formal confirmation on Thursday, police said.

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Rough weather on Wednesday hampered efforts to locate and retrieve more bodies from the sea off the island of Borneo, but conditions improved briefly Thursday morning.

“The weather is clear today. We’re making an all-out effort to search for bodies and locate the fuselage,” search and rescue official Sunarbowo Sandi said from Pangkalan Bun, a town on Borneo with the nearest airstrip to the crash site.

Sandi said foreign experts would join Indonesian transport safety investigators in the search for the wreckage and the black boxes, which are crucial to determining the cause of the crash.

“Ten investigators from the national transport safety committee (KNKT) along with two French and two Singapore investigators will join the search today to locate the fuselage,” he said.

“We hope that an underwater beacon will be able to detect the weak signal transmitted by the ELT (emergency locator transmitter),” he added.

Grieving family members anxiously wait for news on their loved ones.

The transmitter sends a signal supposed to help rescuers find a plane in the event of an accident.

Dozens of navy frogmen and search-and-rescue divers were in the area and ready to go once the fuselage was located, Sandi said.

The plane is believed to be in relatively shallow water of around 25-32 metres.

A US State Department official said Washington would continue to work closely “with technical experts in Indonesia and US Defense Department officials to see how else we can help”.

Washington has deployed the destroyer USS Sampson to help with the search, with a second vessel due to join ships and planes from Australia, Singapore, South Korea and Malaysia already helping Indonesia.

National Search and Rescue Agency chief Bambang Soelistyo said on Wednesday the fuselage had not yet been found, denying reports that sonar imagery showed the aircraft on the seabed.

During searches on Tuesday, which retrieved wreckage giving the first confirmation that the flight had crashed, an air force plane had seen a “shadow” on the seabed believed to be the missing plane. All efforts are now being concentrated there.

Debris found so far includes an exit door, an emergency slide and several suitcases.

Four more bodies in numbered white coffins arrived at Surabaya airport on Thursday, where they were carried by military personnel wearing white gloves and face masks.

Police have taken DNA samples and medical data from dozens of relatives of the victims to aid in identification of the bodies, one of whom was a woman in cabin crew uniform.

President Joko Widodo has promised “a massive search” effort, with priority given to recovering bodies.

-AAP