MOSCOW: The Kremlin on Wednesday said details of a fire that killed 14 crew on a deep-water submersible will not be made public because they include classified information.

The seamen died on Monday in Russia's territorial waters in the country's far-north, but the disaster was only made public Tuesday.

Officials have given little information about the vessel or the circumstances of the accident, with local media reporting the ship was a secretive nuclear-powered mini-submarine.

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

"This information cannot be made public completely," Kremlin spokesman Dmitry Peskov said of the disaster. "It belongs to the category of state secrets."

Peskov said that President Vladimir 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 said that "no decision has been made" about a period of mourning in the northern Russian region.

The defence ministry said the 14 crew were killed by inhaling poisonous fumes after a fire broke out on a "scientific research deep-sea submersible" studying the sea floor.

However the 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 presence of many senior ranking officers on board could suggest the submarine was not on an ordinary assignment.

- 'Conducting important research' -

Minister Shoigu was in Severomorsk, the restricted-access military port in the Russian Arctic, on Wednesday to direct a probe into the accident.

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

He 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."

According to Shoigu, a civilian "representative of industry" was successfully evacuated by the crew that acted "heroically."

The crew managed to evacuate the civilian after which they closed the hatch to halt the spreading of flames, he said.

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

The governor of Saint Petersburg, Alexander Beglov said Wednesday 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.

Putin has ordered a full investigation into what he called a "tragedy".

The incident is the latest in a string of disasters and accidents to hit Russia's navy, with echoes of the sinking of the Kursk submarine in 2000 that claimed the lives of 118 personnel and shook the first years of Putin's presidency.

During a meeting with Shoigu Tuesday, Putin said the submarine in question was "not an ordinary vessel."

"As we know, it's a scientific-research vessel, its crew is highly professional," the Russian leader said.

He 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.

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.

The fire was put out and the vessel returned to a military base in Severomorsk. It is unknown how many were on board the sub. —AFP