Indian navy divers have recovered three severely burned bodies of sailors who had been trapped inside a submarine damaged by twin explosions, a navy spokesman said.

Narendra Vispute said on Friday it was doubtful that any of the other 15 sailors aboard survived.

He told reporters in Mumbai that the conditions of the bodies recovered early on Friday morning suggest that all 18 sailors aboard were killed in the explosions in the sub's home port of Mumbai.

"The bodies are severely disfigured and not identifiable due to severe burns," Vispute said, adding that DNA tests would be used to identify the bodies.

"However, the navy will continue to search every inch of the submarine until no bodies remain to be found.

A press statement from the navy said that while divers had been working around the clock to reach the compartments of the submarine since the explosions occurred, their efforts were hindered by the "oily and muddy waters inside the submerged submarine resulting in total darkness and nil visibility within the submarine even with high power underwater lamps."

AK Antony, the defence minister, said on Wednesday before leaving for Mumbai to assess the situation that the accident was "a loss to all of us [and] a tragedy". 

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

Vinod Kumar Menon, city editor of Mid-Day newspaper based in Mumbai, said that fire started at midnight and went on till 5:30-6am local time.

The Indian news channel NDTV said nearly a dozen fire engines rushed to the dockyard to douse the fire.

The submarine was nearly submerged at its berth in the naval dockyard.

Indian media reports say the 16-year-old Russian-made submarine had recently returned from Russia after undergoing an overhaul and upgrade.

The INS Sindhurakshak had been damaged earlier in a deadly explosion in 2010.

Source: Agencies