NEW DELHI/MUMBAI: Navy chief Admiral DK Joshi on Wednesday resigned after two officers were feared killed and seven sailors injured when a fire erupted on board a submarine, INS Sindhuratna , around 40 nautical miles off Mumbai."Taking moral responsibility for the accidents and incidents which have taken place during the past few months, the Navy chief has resigned. The government has accepted the resignation of Admiral Joshi with immediate effect. Navy vice-chief Vice Admiral RK Dhowan will be discharging the duties of officiating Navy chief, pending the appointment of a regular chief," said a defence ministry statement.In the accident, the Navy said the two officers, a lieutenant commander and a lieutenant, both from the electrical branch, were "still to be accounted for", while the seven sailors were airlifted by Sea King helicopters to INS Ashwini hospital at Colaba."The sailors fell unconscious on inhaling the heavy smoke engulfing the submarine's third compartment. They are now stable," said an officer.An upset defence ministry sought a detailed report from the Navy since this is the second major accident in the country's ageing submarine fleet in the last six months, which has further dented India's underwater combat arm.INS Sindhurakshak, a Russian Kilo-class submarine like INS Sindhuratna, had sunk at the Mumbai naval dockyard, killing three officers and 15 sailors, after a series of internal explosions in its fully-loaded weapons compartment on August 14. INS Sindhuratna, incidentally, was berthed next to INS Sindhurakshak at that time and sustained minor damage to its hull.The accident on Wednesday took place when INS Sindhuratna had just begun its "sea workup phase" after undergoing a refit at the Mumbai dockyard from May to December last year. As part of the procedures, the Western Naval Command's commodore commanding submarines SR Kapoor and his inspection team were on board to test both the crew and the submarine before clearing it for operational deployment.In all, there were 94 personnel on board.Retired senior officers expressed surprise over the sudden decision of the Navy chief to resign taking "moral responsibility" over the spate of accidents involving naval warships in the last seven months."I do not think it was quite necessary. There are many other things that lead to this kind of situation. It is a difficult service," former Navy chief Admiral Sureesh Mehta said. "This is a personal conduct, being an upright officer, he sent his resignation. Once he has taken a decision, there is no point of buckling down or withdrawing it," he added.The former Navy chief said accidents are a part of life in these services and "especially when it comes to submarine and aircraft. The chief is not responsible for it."Senior retired officer Rear Admiral Raja Menon said he did not expect the Navy chief to resign on this ground after various accidents for which responsibility is fixed at various levels after a proper board of inquiry."What the Navy chief has done is contrary to the present standards of public life. I remember when Lal Bahadur Shastri resigned as Railway Minister after an accident but this standard of public life is long gone. There is no such standard now," he said.Menon said there is no accident in the Navy for which blame is not fixed but the Navy chief has "symbolically taken responsibility for all the actions and handed over his resignation."Former Western Commander Vice Admiral Madanjeet Singh said the accidents happening frequently in the Navy were "not professionally complementary" for the force and "the Navy chief has taken his decision which in my opinion is very honourable thing to do as a professional Navy chief ..."(With inputs from PTI)