There was a fire aboard a Russian nuclear submarine at the Zvezdochka ship repair shop in Arkhangelsk Region, krymr.com and TASS reported.

Law-enforcement sources said that the rubber insulation between light and strong boat hulls caught fire following some welding work. About 20 square meters are involved in the fire, says RIA Novosti.

The boat is in dry dock and fire-fighters continued to douse the flames for two hours, managing to localize the fire, said the sources.

"To a large extent, it's just the rubber smoking there," said a source.

The nuclear reactor was suspended before the fire and there was no ammunition on it, said a source. Some of the crew were on the submarine when the fire broke out but there have been no injuries.

According to preliminary reports, a violation of safety procedure was the cause of the fire. The submarine was being remodeled in order to be fitted with a new missile system.

A representative of the repair shop said she "could not confirm or deny" the fire.

The head of the technical department of the Russian Navy command has flown to Severodinsk to investigate the reasons for the fire, said TASS.

-- Catherine A. Fitzpatrick