Workers have downed tools at three South African power stations and more were set to follow as a wage strike began at state-run power utility Eskom, the National Union of Mineworkers (NUM) said.

Paris Mashego, NUM's energy sector coordinator, told Reuters that wage talks with the utility were in deadlock over the weekend.

Eskom provides almost all the power to Africa's most industrialised economy but it was not immediately clear what impact the strike may have on its ability to keep the lights on.

This is a developing story...