Eskom supplies more than 90% of South Africa's electricity but does not generate sufficient cash to meet its debt-service costs and relies on state bailouts to stay afloat.

Nationwide blackouts in the first quarter of the year pushed the economy into a deep contraction. The situation has improved since March due to stable coal supplies and a maintenance overhaul, Mabuza told a press briefing.

"The one area we are focusing on is to ensure we do not put this country through loadshedding again. Whilst we cannot guarantee there will be no loadshedding we are confident we can keep the lights on this summer," he said.

The power cuts are referred to as loadshedding in South Africa.

Eskom's coal stocks were at 50 days, excluding the Medupi and Kusilie power stations, he said, adding that the company planned to undertake plant maintenance on 5,500 MW of capacity over the next seven months.

Coal stocks were at half of required regulatory levels of 50 days or more at the beginning of the year at most power stations.

Medupi and Kusile, currently under construction and not fully operational, are among the largest coal stations in the world but since building started in 2008, both have suffered major breakdowns while costs have escalated.