A fire broke out aboard a Russian nuclear submarine in the Barents Sea, killing two crew members and injuring another, but the navy said there was no radiation threat, Russian news agencies reported Thursday.

The blaze ignited Wednesday night in a mechanics room on the Daniil Moskovsky submarine of the Northern Fleet, which plies Russia's northern and Arctic waters, the Interfax and ITAR-Tass news agencies reported. The ship's nuclear reactor was shut down automatically, the reports said.

"There is no threat of nuclear contamination," Interfax quoted an unnamed Northern Fleet spokesman as saying.

Russia's top naval officer, Adm. Vladimir Masorin, said the likely cause was a short circuit.

A warrant officer and a sailor were killed by carbon monoxide poisoning, Interfax reported. Another sailor was injured.

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The submarine was later towed along the surface to its base at Vidyayevo, news agencies reported. An investigation has been opened on charges of violation of navigation rules.

"We didn't notify our neighbors because there were rather enough ships, in particular, two rescue tugboats in the vicinity of the incident," Masorin was quoted as saying by ITAR-Tass. "We decided to do nothing while at sea, and instead tow it to its home port where it was launched."

No one could be reached immediately at Russian naval headquarters or the Northern Fleet for confirmation.

The Northern Fleet has suffered a series of accidents on its submarines in recent years. The navy suffered its worst post-Soviet disaster when the Kursk nuclear submarine exploded and sank in the Barents Sea in 2000, killing its entire crew of 118.

In August 2003, nine members of a 10-man crew died when their submarine sank in gale-force winds in the Barents Sea as it was being towed to a scrap yard.

ITAR-Tass said that the Daniil Moskovsky has a crew of 96, and that is it armed with PK-55 Granat cruise missiles, as well as Shkval and Vodopad torpedoes.