Three civil society groups have taken the South African government to court over its plan for new coal-fired power, which they say threatens people's right to an environment not harmful to health.
South Africa already has 15 coal plants with a nominal capacity of more than 38,000 megawatts (MW) and is the world's 12th biggest emitter of greenhouse gases.
The intention to build 1,500 MW of new coal capacity is contained in the government's Integrated Resource Plan, a 2019 document laying out the energy mix up to 2030.
At the United Nations COP26 climate summit this month South Africa secured $8.5 billion of financing from wealthy nations to speed up its shift from coal.
Lawyers for the three groups - groundWork, the African Climate Alliance and Vukani Environmental Justice Movement in Action - wrote to Mineral Resources and Energy Minister Gwede Mantashe and energy regulator Nersa in September demanding that the plan for 1,500 MW of new coal capacity be scrapped.
The lawyers said in a statement on Wednesday that the government had not responded to their "letter of demand" and that litigation had now been launched in the high court.
"New coal-fired power flies in the face of our constitutional right to an environment not harmful to health and wellbeing, not only for the present generations but for future ones too," said Nicole Loser, programme head for pollution and climate change at the Centre for Environmental Rights.
"There is no justifiable basis for the limitation of constitutional rights because cleaner and less harmful renewable energy is both a feasible and cheaper alternative to new coal power," the statement continued.
Spokespeople for Mantashe, the mineral resources and energy department and Nersa could not comment immediately.
Mantashe, a former trade union leader, has argued that the transition towards renewable energy should not be rushed.