South African miner Shanduka Coal has reported that an unwarranted strike at the Graspan colliery east of Johannesburg, turned violent leaving seven people injured.

The mine is partly owned by Glencore and witnessed nearly 250 protestors who seized mining equipments before engaging into a violent clash with police officials.

The police restored to firing rubber bullets to quell the protests and later arrested nine striking employees.

Shanduka in its statement said, "The police dispersed the striking employees, who were on mine premises illegally, had seized mine equipment, and were refusing to leave peacefully.

"The industrial action was unlawful, unprotected and in breach of the employees’ contracts of employment," it added.

Mpumalanga province police spokesman Brigadier Selvy Mohlala claimed that the protestors refused to disperse and charged the police lines with heavy earth moving equipments.

"That is when the police used rubber bullets to disperse the crowd," noted Mohlala.

The developments point to the continual unrest in South African coal mining industry with Exxaro facing protests over bonus issues halting operations at five of its mines earlier in March 2013.