It is feared that the submarine’s 53 crew members have run out of oxygen early on Saturday.

“The assumption that the submarine has 72 hours of oxygen is optimistic given the submarine's limited ability to generate oxygen due to its conventional power generation. Therefore, there's a possibility that oxygen might have already run out,” said Achmad Riad, a spokesman for the Indonesian military.

Indonesian Army said that six warships, a helicopter and 400 people had been involved in the search.

Neighboring Singapore, Malaysia and Australia as well as the United States were among nations helping in the search. Other nations, including Germany, France, Russia, Turkey, and Thailand, have offered assistance.