File photo of crew of Russia's nuclear-powered submarine Yekaterinburg as it returns to Gadjiyevo base in Murmansk region
The submarine was under repair in the Zvyozdochka shipyard at the time of the incidentReuters

A Russian nuclear submarine has caught fire in a shipyard in the northern province of Arkhangelsk, according to official RIA Novosti and Interfax news agencies.

The submarine, a K-266 Orel, was under repair in the Zvyozdochka shipyard when the incident took place. The agencies are saying the nuclear reactor has been shut down and weapons have been removed. The fire allegedly started during welding.

There was no word of any casualties.

"The fire affected an area of some 20 sq/m. The insulation between the hulls of the sub is burning," a source told RIA Novosti.

The submarine is part of Russia's Northern Fleet and entered service in December 1992.

In December 2011, a similar blaze engulfed the Yekaterinburg nuclear submarine during welding works at a shipbuilding dock. The massive fire sent flames and black smoke 10m above the vessel. Firemen battled the blaze for a day and a night before sinking the submarine to douse the flames, according to media reports.

Russian officials said at the time that the the nuclear weapons aboard the submarine had been unloaded before the fire. However, the Vlast weekly magazine reported in 2012 that the submarine was carrying intercontinental ballistic missiles armed with four nuclear warheads.

"Russia, for a day, was on the brink of the biggest catastrophe since the time of Chernobyl," Vlast reported.