Astra/Telegram

CCTV cameras captured the moment of the blast in Kopeisk near Chelyabinsk

An explosion at a Russian factory in the Urals producing ammunition and weapons for the military has left at least 10 people dead, reports say.

Witnesses described seeing explosions and a fireball at the Plastmass military plant in Kopeisk, near the city of Chelyabinsk.

Regional governor Alexei Teksler did not specify which factory had been hit but he confirmed the death toll. Tass news agency said 18 other people had been injured.

Authorities have not said what caused the blast but Teksler stressed that “there is no talk of a UAV (drone) attack”.

A day of mourning has been announced and investigators say they have opened a criminal inquiry into the blast.

Teksler said the fire in Kopeisk had been put out.