A fire broke out Thursday on Russia's only aircraft carrier as it underwent repairs in an Artic shipyard, Russian news agencies reported, with at least one worker reported missing.

The Admiral Kuznetsov has been undergoing repairs for more than two years in Murmansk and suffered previous damage in October 2018 when a crane crashed onto its deck.

State news agency RIA Novosti quoted a source in the Zvezdochka shipyard as saying the fire broke out during welding operations. Initial reports said three workers were missing.

More than 400 people were on board when the fire erupted, state news agency TASS quoted a Zvezdochka spokesman as saying.

The Admiral Kuznetsov has been undergoing repairs for more than two years
The Admiral Kuznetsov has been undergoing repairs for more than two years forsvaret / STR

News agency Interfax reported that the fire had spread over an area of about 600 square metres (6,500 square feet).

The Admiral Kuznetsov -- launched in 1985 and the flagship of the Russian navy -- has been undergoing its first major repairs since 1997.

The repairs were expected to be completed by the end of 2020, with the warship rejoining the navy in 2021.

Russia