Australia has offered to “help in any way we can” in the desperate search for an Indonesian navy submarine that has been missing off the coast of Bali with 53 people aboard for over 24 hours.

The 44-year-old submarine, KRI Nanggala-402, was conducting a torpedo drill in waters north of the island of Bali on Wednesday but failed to relay the results as expected, a navy spokesman said.

The submarine was carrying 49 crew members, its commander and three gunners.

An aerial search found an oil spill near the submarine’s dive location and two navy vessels with sonar capability have been deployed to assist in the search, the Defence Ministry said.

A ministry statement said requests for assistance had been sent and Australia, Singapore and India had responded.

Australian defence forces would “help in any way we can”, Foreign Minister Marise Payne told ABC radio on Thursday.

“We are obviously very concerned about these reports. It’s very distressing for families and particularly for the Indonesian Navy,” Senator Payne said.

“We operate very different submarines from this one, but the Australian Defence Force and Australian Defence Organisation will work with defence operations in Indonesia to determine what we may be able to do.”

Singapore has deployed a submarine rescue vessel to help, the city-state’s defence minister said, and Malaysia was also sending a ship.

Indonesia’s military chief Hadi Tjahjanto told Reuters in a text message on Wednesday that contact with the vessel was lost at 4.30am and a search was underway for the submarine and its 53 crew in ocean 95 kilometres off Bali.

“It is possible that during static diving, a blackout occurred so control was lost and emergency procedures cannot be carried out and the ship falls to a depth of 600-700 metres,” the Indonesian Navy said in a statement.

There are grave fears for the 53 crew aboard the sub. Photo: Indonesian Navy

The submarine was built to sustain pressure at a maximum depth of around 250 metres, anything more than that “could be fatal, dangerous”, an official said.

The oil spill found on the surface could also mean there was damage to its fuel tank or could also be a signal from the crew, the navy said.

‘Little they can do’ to get people out

Submarine Institute of Australia secretary Frank Owen told the ABC he believes the Australian Defence Force could provide a remote operating vehicle (ROV) to help map the ocean terrain.

“If it is in the depth of water that’s there, then there will be little they can do to actually get the people out – the only way to get the people out would be to salvage the submarine, and that’s a lengthy process”, Mr Owen said.

Independent Australian senator Rex Patrick, a former submariner, expressed his deep concern but said he thought there was still hope.

“You never know what can eventuate in these situations. I wish our Indonesian friends the very best in their endeavours to quickly find the submarine and I know that the RAN and RAAF will offer all available support in assisting the Indonesian Navy,” Senator Patrick told the ABC.

“This is a chilling reminder of just how dangerous submarine service can be”.

Indonesia’s military chief will hold a briefing in Bali about the search later on Thursday.

The 1395-tonne KRI Nanggala-402 was built in Germany in 1977, according to the defence ministry, and joined the Indonesian fleet in 1981. A two-year refit was completed in 2012 in South Korea.

Indonesia in the past operated a fleet of 12 submarines bought from the Soviet Union to patrol the waters of its sprawling archipelago.

But now it has a fleet of only five – two German-built Type 209 submarines and three newer South Korean vessels.

Indonesia has been seeking to modernise its defence capabilities but some of its equipment is old and there have been deadly accidents in recent years.

-with agencies