Of the 30 corpses recovered so far, 21 were found on yesterday, many of them by a US Navy ship, according to officials.

The Airbus A320 carrying 162 passengers and crew went down Sunday, halfway into a flight from Surabaya, Indonesia's second-largest city, to Singapore.

Minutes before losing contact, the pilot told air traffic control he was approaching threatening clouds, but was denied permission to climb to a higher altitude because of heavy air traffic.

It remains unclear what caused the plane to plunge into the sea. The accident was AirAsia's first since it began operations in 2001, quickly becoming one of the region's most popular low-cost carriers.

Indonesian authorities on Saturday grounded AirAsia flights from Surabaya to Singapore, with the Transport Ministry saying the airline did not have a permit to fly on Sundays. AirAsia said it was reviewing the suspension.

Search teams aboard 13 aircraft and 30 ships expanded their hunt for victims and wreckage on Friday, although 3-meter high waves continued to slow down the operation, said National Search and Rescue Agency Director of Operations Suryadi B Supriyadi.

The vessels included eight sophisticated navy ships from Singapore, Malaysia and the US equipped with sonars for scouring the seabed to pinpoint wreckage and the all-important black boxes.

"Many of passengers believed to be still trapped inside the plane's fuselage and could be discovered soon," Supriyadi said, "God willing, we would complete this operation next week."

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