A member of the Indonesian military looks out of the window during a search and rescue (SAR) operation for missing Malaysian air carrier AirAsia flight QZ8501, over the waters of the Java Sea on December 29, 2014.[Photo/CFP]

China on Monday announced that it will send aircraft and vessel to join the search and rescue work for missing AirAsia flight QZ8501.

"After consultations with the Indonesian government, the Chinese government has decided to send aircraft and vessel to search for the missing AirAsia flight," the defense ministry said in a statement released Monday night.

A navy frigate on routine patrol in the South China Sea is heading for the waters where the jet went missing, the statement said.

An Air Force jet is making preparations and coordinating with the countries on the flight route, the statement said.

Earlier, an Indonesian official told the media that the missing jet with 162 people on board was believed to have sunken into the bottom of the sea.

Should the projection be true, Indonesia needed to cooperate with other countries to bring the wreckage to the surface, said Bambang Sulistyo, head of the National Search and Rescue Agency (Basarnas).