CAPE TOWN - South African police on Monday fired rubber bullets at demonstrators burning tires and stoning cars on a highway into Cape Town in protest against government failures to provide basic amenities.

"The crowd is uncontrollable. The police shot at us. About 20 people have been hospitalised," Luthando Zulu, a community activist, told Reuters. Zulu said the protest had temporarily shut the busy road linking Cape Town with its airport.

Thousands of South Africans from mostly black townships and shantytowns have taken to the streets in recent months to voice anger over the lack of electricity, water and sewage and other services in poor neighbourhoods.

Police admitted they had fired at the crowd but did not confirm reports of injuries.

"There were shots fired by police, not live ammunition, but rubber bullets," Kevin Maxwell, a municipal police spokesman, said. City officials said firefighters had to be withdrawn from the scene due to the violence.

In some cases crowds have attacked and even killed officials of the ruling African National Congress, which had vowed to improve the quality of life for millions of blacks who continue to live on the margins of the country's booming economy.

Zulu said the protesters outside Cape Town were unhappy about the lack of housing at a multi-million dollar flagship settlement that was supposed to take in hundreds of people currently living in shantytowns.