Indian Navy Chief Adm. D.K. Joshi resigned Wednesday after seven sailors were injured and two officers remain missing after smoke filled a submarine off the shore of Mumbai.
Wednesday's incident raises the number of mishaps to 11 since INS Sindhurakshak, also a kilo-class vessel, blew up and sank at a Mumbai harbor in August, killing all 18 crew members on board.
The accident Wednesday aboard the Russian-built INS Sindhuratna occurred off the coast of Mumbai during a routine training exercise, the Hindustan Times reported.
A navy officer said sailors lost consciousness after smoke began filling the vessel. They were transported to a naval hospital in Mumbai.
A source told the Times a fire in a battery compartment that was triggered by a short circuit may have been the cause.
The submarine had been refitted in Mumbai two months ago.
This is the third accident involving the navy's kilo-class boats in less than six months, the Times said. An investigation was ordered after INS Sindhughosh hit the seabed last month.
Joshi, who had previously brushed aside criticism of the Navy's safety record, said he was stepping down to accept moral responsibility for the mishaps.
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