The Defence Ministry has sought a detailed report from the Indian Navy about a fire incident in Mumbai which caused damage to a Kilo-class submarine INS Sindhukesari.
"A detailed report has been sought from the Navy about the fire incident in the Naval dockyards in Mumbai," defence sources said.
The submarine had recently been upgraded by a Russian shipyard and was being readied for operational roles by the force.
Sources said the fire took place within a few days of the submarine returning from Russia after an expensive upgrade.
The Kilo class submarines, named the Sindhughosh class by the Indian Navy, were acquired in the 1980s and have been prone to a number of accidents in recent years as their originally planned service life draws to an end.
The INS Sindhurakshak was lost with its crew in an explosion in 2013 while torpedoes were being loaded, while a fire onboard INS Sindhuratna in 2014 led to two personnel losing their lives.