In a statement released Wednesday night, Indonesia’s Defense Ministry said KRI Nanggala-402, a German-made submarine, lost contact during an exercise in the Bali Strait – a stretch of water between the islands of Java and Bali that connects to Indian Ocean and Bali Sea.
The submarine requested permission to dive or dive at 3 a.m. local time (3 p.m. ET) before losing contact, he said. The statement added that there was an oil spill in the air surveillance near the diving point, around 7:00, local time.
Earlier on Wednesday, military chief Hadi Tjahjanto told Reuters that “they were looking for 53 people in the waters of Bali, 96 km from Bali.”
Singapore and Australia offered to provide assistance.
The 1,395-ton KRI Nanggala-402 was built in 1977 by German shipbuilding company Howaldtswerke-Deutsche Werft (HDW) and joined the Indonesian navy in 1981, according to a statement from the defense ministry.
The submarine underwent a two-year restoration in South Korea, which was completed in 2012, according to the website of the Indonesian cabinet secretariat.
In the past, Indonesia operated a fleet of 12 submarines purchased from the Soviet Union to patrol the waters of its vast archipelago.
But it now has a fleet of only five, including two 209-type submarines built in Germany and three newer ships in South Korea.
Indonesia has sought to improve its defense capabilities, but some of its equipment is still in operation and there have been fatal accidents involving, in particular, the aging of military transport aircraft in recent years.