18 sailors killed as Indian navy submarine explodes in Mumbai

India's navy said all 18 sailors on board a submarine which exploded and sank yesterday were feared dead, and admitted the incident left a dent in the country's defences.

The fully armed INS Sindhurakshak, returned by its Russian manufacturer earlier this year after a major refit following a fatal blast in 2010, exploded in flames in Mumbai shortly after midnight and sank in a military shipyard.

The disaster is thought to be the Indian navy's worst since the sinking of a frigate by a Pakistani submarine in 1971. Defence Minister A.K. Antony described the explosion as the "greatest tragedy in recent times".

"I feel sad about those navy personnel who have lost their lives in service of the country," he said in New Delhi.

Chief of naval staff Admiral D.K. Joshi said no sign of life had been detected on board, even after divers managed to enter through the main hatch in a bid to refloat the vessel. "While we hope for the best, we have to prepare for the worst," he said, adding there was a possibility some crew might be in air pockets.

"It is certainly a dent on the Indian navy's submarine capabilities for the time being."

The blast came days after New Delhi trumpeted the launch of its first domestically produced aircraft carrier and the start of sea trials for the first Indian-made nuclear submarine.