There were also concerns that the vessel could have broken apart as it sunk to depths as low as 700 meters (2,300 feet) - well beyond the depth it is created to withstand.
"We will maximize the effort today, until the time limit, tomorrow at 3 am, " military spokesperson Major General Achmad Riad had told reporters on Friday.
The Indonesian navy has reportedly detected an object with "strong magnetic resonance" at a depth of 50 to 100 meters (164 to 328 feet), the military said at a press conference on Friday, reports CNN.
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According to Indonesian authorities, the KRI Nanggala-402, a German-made submarine, went missing during a military exercise around the Bali Strait on Wednesday.
Navy Chief Yudo Margono said rescuers found several items from the KRI Nanggala 402, which disappeared after its last reported dive Wednesday off the resort island of Bali, including parts of a torpedo straightener, a grease bottle believed to be used to oil the periscope and prayer rugs.
Meanwhile, two Australian ships were heading for the search area including a support ship and a frigate with sonar capabilities, the defence department said in a statement.
Search helicopters and more navy ships left Bali and a naval base in Java at first light heading to the area where contact was lost with the 44-year-old KRI Nanggala-402 on Wednesday as it prepared to conduct a torpedo drill.More news: DOJ To Investigate Minneapolis Police For Possible Patterns Of Excessive Force
"The family is in a good condition and keeps praying", said Ratih Wardhani, the sister of 49-year-old crewman Wisnu Subiyantoro.
Singaporean rescue ships are also expected later Saturday, while Malaysian rescue vessels were due to arrive Sunday, bolstering the underwater hunt, Whimbo said.
Kirby also said Secretary of Defense Lloyd Austin was meeting with his counterpart in Indonesia - Prabowo Subianto - to pursue other means of global assistance. He asked Indonesians to pray for the crew's safe return, while ordering all-out efforts to locate the submarine.
The cause of the disappearance is still uncertain. "So it could be mid-water and unable to use any electrical power", he said. Margono said the oil could have spilled from a crack in the vessel's fuel tank, or the crew could have released the fuel to reduce the submarine's weight in order to surface.More news: Oxygen runs low in India as hospitals battle virus 'storm'
There were concerns that the submarine could have been crushed by water pressure if it sank to depths reaching 700 metres - well below what it was built to withstand.
One of the people on board the boat was the commander of the Indonesian submarine fleet, Harry Setiawan.
But the passing of Saturday's oxygen deadline was likely to mean the Southeast Asian archipelago would be added to a list of countries struck by fatal submarine accidents. Most of its 118 crew died instantly, but 23 men fled to a rear compartment before they later died, mainly of suffocation.More news: Oxford researchers launch human challenge trial to study Covid reinfection