A military submarine missing off the coast of Bali is due to run out of oxygen within hours, sparking grave fears for the 53 sailors on board.
The submarine - carrying 49 crew members, its commander and three gunners - has not been seen or heard from since Wednesday when it was conducting a torpedo drill in waters north of Bali.
The KRI Nanggala-402 vessel lost contact after being granted clearance to dive and could have sunk to a depth of between 600 and 800 metres, well below its safe operating levels.
More than 400 emergency response personnel on board two warships have been searching for the missing vessel - as officials predict it is due to run out of air by Sunday.