The government said in a statement that it had accepted the resignation of Chief of Naval Staff Admiral DK Joshi, who will be replaced on an acting basis by Vice Chief of Naval Staff Vice Admiral RK Dhowan.
A search continued for the two officers after smoke filled parts of a Russian-built submarine on a training exercise off the Mumbai coast in the early hours of Wednesday morning.
The accident comes months after a dockside blast in Mumbai killed all 18 aboard another submarine last August, raising concerns over India’s ageing fleet and crew training.
Seven members of the 94-strong crew were evacuated after inhaling smoke aboard the diesel-powered INS Sindhuratna.
Commander Rahul Sinha, a naval spokesman, said the source of the smoke had been removed, but declined to give details.
“When there is a fire in a submarine, the smoke is extremely toxic. There will be time before we enter the compartments completely,” Sinha said. The two officers could not be accounted for more than 12 hours after the incident.
Without apportioning direct blame, the government said that Joshi had taken “moral responsibility for the accidents and incidents which have taken place during the past few months”.
Defence analysts said submarine crew members in the Indian navy were not getting enough training on one type of vessel before moving to another, increasing risks that minor incidents could have fatal consequences.
“It’s a very ominous situation to be in,” said Uday Bhaskar, a fellow at Delhi’s National Maritime Foundation. “The Indian navy is going through a blighted phase.”
Handling a ship comes with experience and young officers weren’t getting the time needed on smaller vessels before moving onto bigger ones, said Bharat Karnad, a senior fellow of national security studies at the Centre for Policy Research.
“You’re beginning to see a trend and it’s not a happy situation,” said Rajeswari Pillai Rajagopalan, senior fellow at the Observer Research Foundation.
Although India has been operating submarines for decades, their numbers are dwindling with delays in procurement since the turn of the century, Rajagopalan noted.
Older submarines were being retired without being replaced with new ones, and the top political leadership had washed its hands off the matter, she said.
India’s navy has had far fewer accidents than the air force, which has been dogged for years by crashes of Russian-made MiG-21 fighters.
However, most of the country’s fleet of more than a dozen submarines is in urgent need of modernisation. Efforts to build a domestic arms industry have meanwhile made slow progress, with India still the world’s largest weapons importer.
The INS Sindhuratna, a Soviet-built Kilo class vessel, was commissioned in 1988.
After smoke was spotted aboard the submarine at about 6 am (0030 GMT) on Wednesday, crew members sealed the compartments and rescuers airlifted the seven who had inhaled smoke to a naval hospital where their condition is stable, said Sinha.
The submarine was still seaworthy and was being ventilated, said Capt. D.K. Sharma, a naval spokesman.
An investigation was being opened into the cause of the incident which appeared to be less serious than the dockside submarine blast in Mumbai last August.
In that incident, an accidental weapons detonation and fire killed everyone on board the INS Sindhurakshak. It was the most serious maritime loss for India since a 1971 war with Pakistan.