BALI, Indonesia, April 24, 2021 (AFP) – Hopes of rescuing dozens aboard a missing Indonesian submarine faded Saturday as its oxygen reserves were believed to have run out, with the US and Australia joining the hunt in waters off Bali.

While warships, planes and hundreds of military personnel took part in a frantic search for the KRI Nanggala 402, authorities had said the German-built craft was equipped with enough oxygen for only three days after losing power.

But that deadline passed early Saturday with still no sign of the stricken vessel and its 53 crew.

“There’s been no progress yet,” said Navy spokesman Julius Widjojono.

“We are still combing the area.”

The submarine — one of five in Indonesia’s fleet — disappeared early Wednesday during live torpedo training exercises off the Indonesian holiday island.

Despite hopes for a miracle, an oil spill spotted where the submarine is thought to have submerged pointed to possible fuel-tank damage, fanning fears of a deadly disaster.

“The oil spill is a bad sign,” said retired French vice-admiral Jean-Louis Vichot.

“If it’s from the submarine, then it is probably the end.”

There were concerns that the submarine could have been crushed by water pressure if it sank to depths reaching 700 metres (2,300 feet) — well below what it was built to withstand.

The vessel was scheduled to conduct the training exercises when it asked for permission to dive. It lost contact shortly after.

Authorities have not offered possible explanations for the submarine’s sudden disappearance or commented on questions about whether the decades-old vessel was overloaded.

The military has said the submarine, delivered to Indonesia in 1981, was seaworthy.

Neighboring Singapore and Malaysia, as well as the United States and Australia, were among nations helping in the hunt with nearly two dozen ships deployed to scour a search zone covering about 10 square nautical miles (34 square kilometres).

Australia’s HMAS Ballarat arrived on Saturday with a US P-8 Poseidon aircraft also helping to look for the craft.

Singapore’s MV Swift Rescue — a submarine rescue vessel — was expected later Saturday.

Indonesia’s military said earlier it had picked up signs of an object with high magnetism at a depth of between 50 and 100 metres (165 and 330 feet), fanning hopes of finding the submarine.

By Sonny Tumbelaka