Johannesburg - Greenpeace is protesting at a coal-fired power station the environmental group believes South Africa does not need.
Greenpeace spokesperson Fiona Musana said the protest started early on Monday, with activists locking the gates of the construction site. She added six activists then climbed pillars at the site, and planned to spend the night on the pillars.
Musana said: "Construction of this place should stop now."
Eskom said it needs Kusile, expected to be completed in 2016, and another coal plant under construction because of rising electricity demand. The state-owned utility also has renewable projects planned.
Coal electricity plants are the main source of greenhouse gas emissions by South Africa, which hosts climate change talks later this year.