The AirAsia plane that went missing with 162 people on board after takeoff from Indonesia is likely at the bottom of the sea, Indonesia's National Search and Rescue Agency chief said as aircraft and ships were dispatched to search for the jet.



"Based on the coordinates given to us and evaluation that the estimated crash position is in the sea, the hypothesis is the plane is at the bottom of the sea," Bambang Soelistyo told reporters on Monday.



"That's the preliminary suspicion and it can develop based on the evaluation of the result of our search."



First Admiral Sigit Setiayana, the Naval Aviation Center Commander at the Surabaya air force base, said that 12 navy ships, five planes, three helicopters and a number of warships were searching an area of east and southeast of Indonesia's Belitung island and nearby waters.



Malaysia, Singapore and Australia have joined the operation.



The Airbus A320-200 went missing after air traffic controllers lost contact with the aircraft about 45 minutes after it left Juanda international airport at Surabaya in East Java at 5:20am on Sunday (22:20 GMT Saturday).



Shortly before disappearing, AirAsia said pilots of the plane had asked permission from Jakarta air traffic control to change course and climb above bad weather in an area noted for severe thunderstorms.