A huge fire has broken out at one of Russia’s largest heavy machinery factories in Yekaterinburg.

Images and footage of the incident, posted on social media, show a large cloud of black smoke rising from the Uralmash facility.

Uralmash produces equipment for mining, metal works, the cement industry and energy facilities including nuclear power plants.

The cause of the blaze remains unclear, but eyewitness accounts described hearing a loud explosion at the plant, sparking a fire covering an area of 4,500 square metres, Russian media reported.

The fire caused the roof of a 300 square metre workshop, which contained 24 cylinders of flammable oxygen and propane gas, to collapse, Russia’s Ministry of Emergency Situations posted on Telegram.

Workers were evacuated from the site, and a team of 64 firefighters brought the blaze under control within an hour, the ministry said.