Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
Suspended Gallo Records employees have distanced themselves from the bombing incidents in which two houses belonging to company workers were destroyed.
The houses in Dobsonville and Jabulani, Soweto, were petrol-bombed on Tuesday by unknown people. The attacks happen as 31 suspended Gallo workers face a hearing after refusing to work overtime.
Worker representative Richard Kobedi said: "As far as we know none of our comrades are responsible for this action.
"We are highly disciplined, we cannot resort to such measures to make our point. There are channels to fight for workers' rights, but attacking people's property is not one of them," he said.
Police spokesman Inspector Kay Makhubela says there is still no evidence to link the suspended workers to the incidents.
He says police are patrolling the area.