Protesters have clashed with police in a South African township in the worst disturbances since Jacob Zuma, the country's president, took office in May.

Thousands of people protesting over lack of basic services in Siyathemba township, 90km southeast of Johannesburg, hurled stones at police who fired tear gas and rubber bullets at the demonstrators on Wednesday.

The unrest, with scenes reminiscent of violence against foreigners last year that killed 62 people, threatens to undermine South Africa's hope of showing a positive image with less than a year to go before the football World Cup.

Zuma's pledge to do more to help poor South Africans was the main plank of the the ruling ANC's election manifesto and the increasing violence will put pressure on the president to deliver on his government's promises.

In Meyerton, south of Johannesburg, residents occupied farmland in protest at being evicted from their temporary settlement.

Finanancial crisis

Many poor South Africans complain they have not seen any benefits since white minority rule ended 15 years ago.

But the government is limited in its actions by South Africa's first recession in 17 years, a result of the global financial crisis, and is wary of any policies that might discourage local or foreign investment.

Nic Borain, an independent South Africa analyst, said: "This was always going to be a problem for Jacob Zuma; a pro-poor government coming to power at the height of the global recession.

"This is going to be the real challenge ... I don't think it is a crisis for the Jacob Zuma government, but I think it is a challenge." 

Trade unions, whose support was instrumental in Zuma's rise to power, have also been flexing their muscles since he took office, with stoppages to demand more pay and threats of strikes.