At least three people have been killed and over 80 injured as a train derailed on the Moscow Metro on the Arbatsko-Pokrovskaya dark blue Metro line on Tuesday morning.

A statement from the metro said only that a train derailed on the network’s blue line, without providing any details, the AFP news agency reported.

At least three people have been killed and over 80 injured in Moscow Metro crash (photo RIA Novosti)

There is no word as to the cause of the crash, in the west of the city.

The Moscow metro is one of the oldest and most extensive underground railway systems in the world.

Some of the most seriously injured passengers were taken to hospital by helicopter, Russian TV said.

The train derailed in a tunnel between stations.

News of the derailment was preceded by reports of smoke detected on the dark blue line of the Moscow Metro. Later, Moscow’s emergencies agency denied reports of smoke and said a sudden failure in the electricity supply to a conductor rail could have caused the accident.