Indonesia’s navy says items have been found from a missing submarine, indicating the vessel with 53 crew members has sunk.

Navy Chief Yudo Margono said that rescuers found several items including parts of a torpedo straightener, a grease bottle believed to be used to oil the periscope and prayer rugs from the submarine.

“With the authentic evidence we found believed to be from the submarine, we have now moved from the sub miss phase to sub sunk,” Mr Margono said.

Indonesia earlier considered the submarine that disappeared on Thursday off Bali as just missing.

But it now declares the submarine as officially sank with no hopes of finding any survivors.

Officials said oxygen supply for its 53 crew ran out early on Saturday.

A US reconnaissance plane, a P8 Poseidon, landed early Saturday and was set to join the search, along with 20 Indonesian ships, a sonar-equipped Australian warship and four Indonesian aircraft.

Singaporean rescue ships were also expected later on Saturday, while Malaysian rescue vessels were due to arrive on Sunday, bolstering the underwater hunt, Indonesia military spokesperson Djawara Whimbo said earlier Saturday.

He had said Indonesia’s hydrographic vessel was still unable to detect an unidentified object exhibiting high magnetism that was earlier detected located at a depth of 50 to 100 metres (165 to 330 feet).

Indonesian President Joko Widodo had ordered all-out efforts to locate the submarine and asked Indonesians to pray for the crew’s safe return.

The search focused on an area near the starting position of its last dive where an oil slick was found but there was no conclusive evidence so far the oil slick was from the sub.

Mr Margono, the navy chief, had said oil could have spilled from a crack in the submarine’s fuel tank or the crew could have released fuel and fluids to reduce the vessel’s weight so it could surface.

The navy however, believes the submarine sank to a depth of 600-700 metres (2,000-2,300 feet), much deeper than its collapse depth of 200 metres (655 feet), at which water pressure would be greater than the hull could withstand.

The cause of the disappearance is still uncertain.

The navy has said an electrical failure could have left the submarine unable to execute emergency procedures to resurface.

The German-built diesel-powered KRI Nanggala 402 has been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the Indonesian defence ministry said.

Indonesia, the world’s largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.