Four miners have been killed and two injured in an explosion that ripped through the Gai copper mine in the Orenburg Region in south-east Russia.

The incident occurred when the miners were planting explosives in the pit to extract copper at the mine owned by Gaisky GOK.

Gaisky GOK spokesman told RIA Novosti news agency that the two injured are in hospital.

Two squads of paramilitary mine rescue unit are currently working at the site to search and evacuate the remaining miners from the pit.

A task force of Gai fire department rushed to the site.

"The incident occurred when the miners were planting explosives to extract copper."

The Ministry of the Russian Federation for Affairs for Civil Defence, Emergencies and Elimination of Consequences of Natural Disasters (EMERCOM) said that the operations at the mine have been temporarily suspended.

Investigation is on to find out the exact cause of the accident.

The mine accident comes four years after the Raspadskaya coal mine explosion near Mezhdurechensk in Kemerovo Oblast, Russia.

The Raspadskaya coal mine explosion that occurred in May 2010 was caused by the build-up of methane gas; it resulted in 66 deaths and left 24 missing.

Image: Paramilitary teams are working on rescue operations at the Gai copper mine. File photo: courtesy of EMERCOM of Russia.