Fourteen Russian sailors were killed on board a 'secret' submarine, leaving Vladimir Putin to cancel an emergency briefing.

The Russian submariners died after a blaze started on their nuclear submersible in the Arctic yesterday.

The research vessel, described as a nuclear-powered AS-12 Losharik, was carrying out a survey of the sea floor on Monday and the crew died of smoke inhalation, the Russian defence ministry told state news agencies.

The ministry did not name the vessel that caught fire and Russian media reported it was the country's most secret submarine, a nuclear-powered vessel designed for sensitive missions at great ocean depths.

President Putin cancelled a scheduled appearance and summoned his defence minister to be briefed on the situation.

Norwegian Radiation and Nuclear Radiation Authority said the Russian counterparts told them a 'gas explosion' occurred on board the submarine.

An undated aerial view of the Russian Navy base in Severomorsk on the Barents Sea in the Arctic Circle

Authorities in nearby Norway said they were monitoring but had not detected abnormally high levels of radiation.

The fire was extinguished and the vessel was taken back to the Russian Northern Fleet's base in Severomorsk on the Barents Sea.

It was put out due to the self-sacrifice of crew members, the Russian authorities said, but did not confirm what is thought to have started the blaze.

Although the vessel was said to be a carrying out scientific research, military analysts have suggested one of its possible missions could be disrupting communication cables on the ocean bed.

'This is a great loss for the navy,' Russian President Vladimir Putin said in a televised meeting with his defence minister, Sergei Shoigu.

'We express our deepest condolences to the families of those who died. We will do everything we can to support them,' said Putin, who cancelled a public engagement this afternoon to deal with the incident.

In his meeting with his defence minister, Putin said that of the 14 dead, seven held the rank of captain, first class, and two were holders of the Hero of Russia, the highest military award issued in the post-World War Two period.

'This is not a regular vessel, as we know, it's a scientific research vessel. It's a highly professional crew,' Putin said.

Decommissioned Russian nuclear submarines are shown in their Arctic base of Severomorsk, the Kola Peninsula, Russia, in a file photo from 1998

President Putin told Shoigu to fly to Severomorsk, the Russian naval base on the Barents Sea where the submarine is now located, to find out what caused the incident, and then report back to him.

The Defence Ministry said in a statement that the fire broke out while the submersible was measuring sea depths in Russian territorial waters

An investigation has been launched by the commander-in-chief of the navy to establish the cause, the ministry were quoted as saying.

'On July 1 in Russian territorial waters a 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,' Interfax cited a ministry statement as saying.

'Fourteen submariners died as the result of smoke inhalation ... Work is underway to establish the cause of the incident. The investigation is being conducted by the commander-in-chief of the navy.'

The ministry added that the fire had been put out due to the crew's 'self-sacrifice.'

The apparatus on board was being used to study the depth of the seabed for the Russian navy.

But a military expert, speaking to AFP on condition of anonymity, rubbished the claims.

Russian rescue personnel return from a dive in a mini submersible to the nuclear-powered Kursk submarine which sank in the Barents Sea in 2000, killing all 118 crew members on board

'Usually it's a cover for different type of work conducted on the seabed' like laying cables, the expert said.

The RBC newspaper, citing a source in law enforcement agencies, said the accident took place in the submersible deployed from the AC-12 nuclear submarine known as Losharik.

The Losharik, which entered service in 2010, is the most advanced and most obscure Russian submarine. It is named after a Soviet-era cartoon character, a toy horse made of small spheres.

The name is apparently explained by the unique design of its internal hull, which is made of several titanium spheres capable of withstanding high pressure at great depths.

In 2012, the Losharik was involved in research intended to prove Russia's claim on the vast Arctic seabed. It collected samples from the depth of 2,500 metres, according to official statements at the time. Regular submarines can typically dive to depths of up to 600 metres.

Some observers speculated the Losharik was capable of going as deep as 6,000 metres, but the claims could not be independently confirmed.

Russian President Vladimir Putin (left) attending the Navy day in the city of Severomorsk in 2014

Analysts suggested one of its possible missions could be disrupting communication cables on the ocean bed.

The Losharik is carried under the hull of a mother submarine, the nuclear-powered Orenburg.

Russian news reports said that while the Losharik officially belongs to the Northern Fleet, it answers directly to the Defence Ministry's Department for Deep-Sea Research, reflecting the high sensitivity of its missions.

The Russian navy also uses Priz-class and Bester-class deep water vehicles, which have hulls built of titanium and are capable of operating at a depth of 1,000 metres. They have a crew of two and are primarily intended for rescuing submariners in case of incidents.

Such vessels are transported to the area of operation by a carrier vessel and can operate autonomously for up to 120 hours.

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

The Marshal Ustinov missile cruiser in the port of Severomorsk last month

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

An inquiry into the Kursk tragedy found that a torpedo had exploded, detonating all the others.

Putin, who stayed on holiday for several days after the disaster, was severely criticised for his response.

Moscow also controversially turned down foreign offers of assistance for the rescue effort.

In another accident in 2008, twenty people - three naval officers and 17 civilians - were killed by poison gas after a vessel's fire-extinguishing system was accidentally activated during trials in the Sea of Japan.

In 2011, one of Russia's biggest nuclear submarines caught fire while undergoing repairs in dock in the northern Murmansk region.

Later it was reported the sub was armed with long-range nuclear missiles when it caught fire.