Eskom said the planned outages were necessary to prevent the collapse of the country’s electricity grid.

The power cuts in South Africa have also affected electricity supplies in Zimbabwe – where Eskom exports up to 400 megawatts every day.

South Africa's neighbour is already suffering country-wide power cuts that can last up to 18 hours a day. Zimbabwe’s electricity utility said Eskom’s problems were making the situation worse.

The last round of blackouts in South Africa was seven months ago and Eskom has admitted these latest outages took it by surprise. The problems mean the company’s woes are far from over.

The power cuts themselves are putting further pressure on an ailing economy. The blackouts earlier this year hampered economic growth.

caption: Most of Eskom's power plants run on coal, an abundant resource in South Africa