Indonesia's president ordered an all-out effort to find a missing submarine in a race against time to save the 53 crew members, whose oxygen supply defense chiefs said would last only until Saturday.

Indonesia sent a helicopter and five ships to search waters north of the holiday island of Bali but found no signs of the KRI Nanggala-402, which went missing early on Wednesday during a torpedo drill.

"I have ordered the military chief, navy chief of staff, the search and rescue agency and other instances to deploy all the forces and the most optimal efforts to find and rescue the submarine crew," Indonesian President Joko Widodo said on Thursday.

"The main priority is the safety of the 53 crew members (with 49 crew members, three weapons specialists and a ship commander)." 

Yudo Margono, the country's navy chief of staff, said the search was being aided by calm conditions but the crew's oxygen would last for 72 hours during a power blackout.

"We lost contact (with the vessel) yesterday at 3 a.m., so it can last until Saturday 3 a.m.," he was quoted as saying by CNA news. 

The vessel had been cleared for use and was in good condition, he added.

The 1,395-tonne vessel was built in Germany in 1977, according to the Indonesian defense ministry, and joined the Indonesian fleet in 1981. It underwent a two-year refit in South Korea that was completed in 2012.

Several countries had responded to requests for assistance, with Malaysia and Singapore sending ships and Australia offering "help in any way we can," Indonesian authorities said.

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

The oil slick could indicate damage to the vessel or could be a signal from the crew, the navy said. Yudo said an item with "high magnetic force" floating at a depth of 50 to 100 meters was also found.

Indonesia has been seeking to modernize its defense capabilities but some of its equipment is old and there have been fatal accidents in recent years.

Indonesian Defence Minister Prabowo Subianto said it was "imperative" that Indonesia modernizes its defense equipment faster, but did not suggest there had been problems with the missing vessel.

(With input from Reuters)