"The INS Chakra sonar has been damaged. Two panels were dislodged. An inquiry has been initiated," said Admiral Lanba, informing that a joint India-Russia team had assessed the damage. The Navy chief was addressing a press conference to mark Navy Day.
INS Chakra is a Russia-made, nuclear-propelled, hunter-killer submarine that India has taken on a 10-year lease from Russia.
The navy has not disclosed how the damage took place on the vessel, which has not sailed for some time now.
India leased the INS Chakra in 2012 for approximately US$700 million and is in talks to lease another. The Akula Class submarine is currently berthed at Visakhapatnam.
One of the quietest nuclear submarines around, the INS Chakra can stay underwater as long as it wants, unlike conventional submarines that need to surface to charge their batteries often.
The INS Chakra can do over 30 knots - more than twice the speed of conventional submarines. It can go upto a depth of 600 metres. The submarine is managed by 80 crew members.
INS Chakra was expected to be inducted into Indian Navy way back in 2010, but after an on-board accident in 2008, in which several Russian sailors died, the delivery was stalled.
The only other nations with nuclear-powered submarines are - US, Russia, UK, France and China.