At least 14 sailors have been killed in a fire that erupted on board a secret Russian navy submarine, the country’s Defence Ministry has confirmed.

The crew members died after inhaling poisonous fumes from the blaze, which broke out on Monday local time while the vessel, nicknamed Losharik, was performing tests in Russia’s territorial waters.

“Fire broke out on board a deep-water scientific research vessel that was studying the marine environment of the world ocean on behalf of the Russian navy,” the ministry said in a statement.

Russian media reported the submarine was the country’s most secret submersible, a nuclear-powered vessel designed for sensitive missions at great depths.

Those on board the submarine successfully put out the blaze, and the vessel is currently stationed at the Russian Northern Fleet’s base at the Arctic port of Severomorsk in Murmansk. 

An aerial view of the Russian Navy base in Severomorsk. Photo: AAP

An official investigation has been launched to establish the cause of the fire.

Russian president Vladimir Putin reportedly cancelled his schedule so he could meet with defence minister Sergei Shoigu after the fateful incident.

Mr Putin ordered Mr Shoigu to fly to Severomorsk to oversee the investigation and report back to him personally.

“It’s a huge loss for the navy. I offer my sincere condolences to the families of the victims,” the Russian President said.

Mr Putin ordered Defence Minister Shoigu to oversee the investigation. Photo: The Kremlin

He added that the vessel had a special mission and an elite crew.

“It’s isn’t a regular vessel. It’s a research vessel with a highly professional crew,” Putin said, adding that seven of the dead had the rank of captain and two were awarded the nation’s highest medal, the Hero of Russia.

The ministry didn’t say how many crew members were on board when the fire erupted and if there were any survivors.

It didn’t give a cause for the fire or provide any additional information about the incident.

The ministry’s statement on Tuesday said the submersible is intended for studying the seabed, but didn’t give its name or type.

The Russian navy uses Priz-class and Bester-class deep water vehicles, which have a hull built of titanium and are capable of operating at a depth of 1000 metres. They are transported to the area of operation by a carrier vessel and can operate autonomously for up to 120 hours.

The blaze marks the deadliest Russian naval incident since 2008, when 20 died when a firefighting system was accidentally initiated while the Nerpa nuclear-powered submarine of Russia’s Pacific Fleet was undergoing trials.

In the deadliest naval incident in post-Soviet Russia, the Kursk nuclear submarine exploded and sank on August 12, 2000, during naval manoeuvres in the Barents Sea, killing all 118 crew members.

-with AAP