Two people have been killed following a "seismic related fall" at one of Harmony Gold Mining Company's mine's in Welkom, the company said on Tuesday.
The mining giant in a statement said an investigation into the deaths was underway.
"We regret to advise that two of its employees were fatally injured in a seismic related fall of ground incident at its Joel mine near Welkom in the Free State on Tuesday morning. "
The statement added: "Management express their deepest condolences to the deceased employee’s family, friends and colleagues."
Former Mineral Resources Minister Mosebenzi Zwane last year urged mines to step up health and safety efforts after three miners died at a Harmony Gold mine in August.
He had said he was concerned with accidents in the industry. He called for a prioritisation of safety saying government would regularly conduct inspections.