"Given the long lead-time of building additional new nuclear capacity, upfront planning is necessary for security of energy supply to society into the future," said the ministry said in a statement.

The government had decided to seek information on a nuclear-build programme "at a pace and sale that the country can afford", said the ministry.

South Africa is the only country in Africa to have a civil nuclear programme, with two reactors at the Koeberg power plant, in service for more than 30 years. They produce 1,860 megawatts, or about 4 percent of the country's total energy.

Currently, 90 percent of the country's electricity is generated from coal-fired stations. But its plants are ageing and poorly maintained, causing repeated power outages that have severely handicapped the country's economy.

The government last year dropped controversial plans to build eight nuclear power stations, deals that had been initiated by former president Jacob Zuma.