The Cullinan mine.
Petra Diamonds said on Monday it was in the process halting operations at its Cullinan, Finsch and Koffiefontein mines in South Africa after State utility Eskom asked the miner to reduce its electricity load.
Production, hoisting and processing have stopped with immediate effect and Petra Diamonds is now removing all people from underground, except those required for essential services, it said in a statement.
Eskom on Monday said it would cut up to 6 000 MW of power from the national grid as heavy rain and flooding triggered failures at its Medupi plant.
Petra said only pumping to prevent flooding and ventilation for safety was being allowed at the mines.
Petra, which has been fixing its balance sheet after spending much of this decade investing in its flagship Cullinan mine, said it would issue an update once its knows how long the load curtailment will last and what impact this is likely to have on its production performance.