A protest at the Medupi power station construction site near Lephalale, in Limpopo, led to the closure of the site on Tuesday, Eskom said.

"The protest action by the workers, who are employed by contractors on the Medupi project, resulted in some damage to vehicles, but there were no injuries," spokeswoman Hilary Joffe said in a statement.

She said of the 9000 workers employed at the site, 500 participated in the protest.

According to Limpopo police, "thousands" of protesters torched two buses and damaged four vehicles.

"Residents alleged that Eskom is employing foreign-experienced boilermakers and not considering the [local] residents for the positions," Brigadier Hangwani Mulaudzi said.

Two buses were set alight and two police vehicles and two cars damaged. Police had deployed members of the public order policing unit to stabilise the situation. Mulaudzi said police condemned violence by people who did not want to engage in dialogue when they had problems.

"As the police, we will not hesitate to take action against anyone who transgresses the law," he said.

No arrests had been made and no injuries reported.

Tuesday's incident followed the closure on Friday of Eskom's construction site at Kusile in Delmas, Mpumalanga, also due to a protest.

Joffe said the Medupi project was still on track for its scheduled power-up at the end of 2012, despite the disruption.