Heavy rains have battered parts of South Africa, submerging whole neighbourhoods and flooding coal mines and power stations in a nation already hit by electricity blackouts.

At least 700 homes have been washed away near the capital, Pretoria, public broadcaster SABC reported.

The state-run power utility warned of further electricity cuts, saying heavy rains had affected its operations.

The cuts have halted gold and diamond production at some leading mines.

Harmony Gold said it had called off underground shifts because of the power cuts, known as load shedding in South Africa.

Petra Diamonds said it was "removing all people from underground, except those required for essential services, with only pumping to prevent flooding and ventilation for safety being allowed".