Russia's only aircraft carrier, which has regularly been described as the worst in the world, burst into flames on Thursday while undergoing repairs.

10 people are injured, three are unaccounted for, and six were saved from the Admiral Kuznetsov, which was at port in Murmansk, according to reports from Russian state news agencies TASS and Interfax.

"Ten people were injured: they were mostly poisoned by combustion products," a source told TASS. Six people are in intensive care.

TASS reported that the fire started in the engine room on the second deck, then has spread to the size of 120 square meters.


Firefighters are battling the blaze with limited success, according to the news agencies.

Aleksey Rakhmanov, head of the state-run United Shipbuilding Corporation, told Interfax that "a human factor" may have caused the fire.

Russia's Northern Fleet reported two firefighters were injured while fighting the blaze, TASS reported.

The aircraft carrier was undergoing major repairs at Russia's Arctic port in Murmansk, also known as the Barents Sea port.

The ship was seriously damaged in October, when a crane toppled over and smashed a 214-square-foot hole in the hull.

The aircraft carrier is has long been beset with operational problems.

On a 2016 mission in Syria, the carrier saw the loss of two onboard fighter jets in just three weeks.

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