An Indonesian Navy submarine with 53 people on board has gone missing amid fears it sank during a military exercise off the waters of Bali.

The navy has deployed several warships to look for the missing crew, and officials fear the ship sank to the bottom of a trough with a depth of 2,300ft, reports Kompas.

The German-made submarine, KRI Nanggala-402, was conducting a torpedo drill in waters 60 miles north of the island of Bali on Wednesday, but failed to relay the results as expected, according to a navy spokesman.

The country’s military chief said the navy is now seeking help from Singapore and Australia.

Contact with the submarine was lost at around 4.30 am on Wednesday morning, said TNI Commander Marshal Hadi Tjahjanto.

“We are still searching in the waters of Bali, 60 miles from Bali, (for) 53 people,” military chief Hadi Tjahjanto told Reuters in a text message, adding “tomorrow I will immediately go to the location.”

The military chief stressed that help in the search for the submarine and missing crew members had been sought from Singapore and Australia.

Representatives of the defense departments of the two countries did not immediately respond to requests for comment.