Reuters

A huge explosion and fire have destroyed India's most advanced diesel-electric submarine, the INS Sindhurakshak , which was docked at a high-security military dockyard in Mumbai. About 18 sailors are trapped in the vessel, which tilted and has sunk nose down. (See Pictures) Defence Minister AK. Antony said crew members inside the Russian-built INS Sindhurakshak had died. He gave no detailsThere has been no contact established yet with the personnel feared trapped on board. It is not clear if some sailors jumped to safety before it went down. Some injured personnel have been admitted to a navy hospital in Mumbai's Colaba but it is not clear if they were from the INS Sindhurakshak.There is no word on casualties or on what caused the explosion, amid speculation on whether a fire caused weapons on board to explode. According to sources in the Ministry of Defence, early reports said the explosion happened in the armament chamber of the fully-armed submarine, which carried heavy weight torpedos and "Klub" anti-shipping and land attack missiles.Navy divers are conducting rescue and salvage operations, but have not been able to enter the submarine yet. A Navy statement said the submarine, refurbished three months ago in Russia at a cost of Rs 480 crore, is "submerged at her berth with only a portion visible above the surface." (Navy's full statement) Reports said another submarine docked close by, the INS Sindhuratna, managed to pull away, but has been damaged in the explosion.Defence Minister AK Antony will visit Mumbai today; Navy Chief Admiral Devendra Kumar Joshi has left for Mumbai.The internal explosion occurred a little after midnight yesterday. The fire was brought under control after 3 am by 16 fire tenders.

The loss of the 16-year-old submarine is a major setback to the Navy's operational preparedness. It had been fitted with an improved warfare system and was expected to serve for at least 10 years more. India has only 14 submarines; it needs 20.A board of inquiry has been set up to determine the cause of the accident.