The seamen died on Monday as a result of poisoning from the fumes of the fire on a submersible in the Barents Sea in Russia's territorial waters but the disaster was only made public by the defence ministry on Tuesday.

The tragedy in the far north has echoes of the sinking of the Kursk submarine in 2000, also in the Barents Sea, that claimed 118 lives and shook the first year of Vladimir Putin's presidency.

Officials have released little information, saying the crew of a research submersible was studying the sea floor in the interests of the navy but Russian media reported the ship was a top-secret nuclear-powered mini-submarine.

President Putin did not go to a military base in the northern city of Severomorsk where the vessel is now, dispatching his defence minister instead.

The Kremlin also did not immediately declare a nationwide day of mourning for the victims.

On Wednesday, Defence Minister Sergei Shoigu said there were survivors of the accident, without clarifying how many.

Putin's spokesman explained the secrecy surrounding the tragedy by saying the information "belongs to the category of state secrets."

He said that Putin was informed immediately after the fire.

"It is completely normal when this kind of information is not made public," Peskov said, adding that this was "within the law of the Russian Federation."

Peskov also said that "no decision has been made" about a period of mourning.

Several media outlets including independent newspaper Novaya Gazeta newspaper cited sources as saying that the accident took place on an AS-12 nuclear mini-submarine, which is capable of going to extreme depths.

The acting governor of Saint Petersburg, Alexander Beglov, said that the crew was based in the city.

Names of members crew have not been officially released. By Russian law, publishing names of servicemen engaged in conflict or special operations is illegal.

The presence of many senior ranking officers on board could suggest the submarine was not on an ordinary assignment, military experts say.

Putin has said the victims included seven Captain First Rank officers -- the most senior staff officers in the Russian navy -- and two have been awarded Hero of Russia, a top title given out by the president.

- 'Conducting important research' -

Shoigu - who was on Wednesday in Severomorsk, the restricted-access military port in the Russian Arctic -- said the vessel was conducting "important research on the hydrosphere of the earth" in the Barents Sea and that those on board were "unique military specialists."

"Fourteen crew members died, the rest were saved," he said without disclosing the total number of the seamen onboard.

He said that a civilian "representative of industry" was successfully evacuated by the crew that acted "heroically."

After evacuating the civilian the crew closed the hatch to halt the spreading of flames, Shoigu added.

"They fought for the ship to survive until the end," he said, adding that the seamen would be posthumously given state awards.

- Echoes of Kursk disaster -

Orthodox cathedrals in the Arctic city of Murmansk and in Kronstadt, a town and naval base in the Gulf of Finland, will hold services in their memory.

The navy was reportedly considering burying the victims in Saint Petersburg's historic Serafimovskoye cemetery, near the graves of those who died in the Kursk submarine.

In August 2000, the Kursk submarine sank in the Barents Sea with the loss of all 118 aboard.

An inquiry 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.

Putin has ordered a full investigation into what he called a "tragedy," saying the submersible was "not an ordinary vessel."

A military expert, who spoke to AFP on condition of anonymity, rubbished claims that the fire happened during scientific research.

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