Jakarta, Dec 30 (IANS): More countries were sending planes and ships Tuesday to join an expanding search operation in the Java Sea where an AirAsia plane is believed to have disappeared as the aerial hunt entered third day.

Around 30 ships, 15 fixed-wing aircraft and seven helicopters from Indonesia, Malaysia, Singapore and Australia had been scouring the missing flight QZ8501 in some 10,000 square nautical miles Tuesday, Xinhua quoted Bambang Sulistyo, head of the Indonesian National Search and Rescue Agency as saying Tuesday.

He told a local TV that the search would be expanded to land areas with helicopters beginning to comb land on Kalimantan as well as islands in the area. So far, the search has been focused on the Java Sea between the islands of Sumatra and Borneo.

Meanwhile, more countries were joining the international search efforts for the Airbus A320-200, which was flying from Surabaya in Indonesia's East Java province to Singapore on Sunday with 162 people on board.

China said Monday it would send a warship and an air force jet to help look for the missing AirAsia plane.

South Korea was also sending a surveillance plane to join the Indonesia-led search operation and an aircraft from Thailand also planned to join the search Tuesday.

Although no significant clues or wreckage were found over the past two days, the Indonesian authorities said Monday that they would check an oil slick spotted some 100 nautical miles (185 km) off the east coast of Belitung island.

"We haven't been able to confirm, however, whether it was the fuel of the AirAsia aircraft," an air force spokesman Hadi Tjahnanto said.

The AirAsia flight disappeared from the radar screen at 6:17 a.m. local time Sunday (2317 GMT Saturday), 42 minutes after it took off from Surabaya.

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