Cape Town — South African protesters angry over water shortages shut down part of the country's longest highway with rock barricades and burning tires.

Police described the situation in Ventersburg in the Free State province as volatile. The rural town is a popular refueling and resting place for motorists and truckers travelling on the N1 highway, which stretches from Cape Town in the south to the Beit Bridge border post with Zimbabwe in the north.

Warrant Officer Loraine Earle says the Welkom Public Order Policing Unit is on the ground monitoring the situation. She says they have spoken to some of the protesters and asked about their demands.

"They started this morning to protest. It's because of the water situation in town. It's now for the past few weeks that they don't have water," she said. "Members are on the scene. They're monitoring the situation and nobody was arrested as yet."

She says they have had water problems in Ventersburg on-and-off for the past seven weeks with no water for the past three weeks.

Those using the highway at Ventersburg have been advised to take alternative routes.