Supporters of the ruling African National Congress (ANC) and opposing Congress of the People (COPE) sing and dance together next to a polling station.

Supporters of the ruling African National Congress (ANC) and opposing Congress of the People (COPE) sing and dance together next to a polling station. Photo: AFP

Twenty years after South Africans of all colours wowed the world by voting to end apartheid, they shrugged off sporadic violence and flocked to the polls for another landmark election.

The African National Congress of liberation icon Nelson Mandela is expected to win a fifth term in power, but Wednesday's election is being closely watched for the votes of the "born frees" and expected gains by parties to both the left and right.

Some 25 million voters were registered for the elections, still determined to exercise their hard-won freedom at more than 22,000 polling centres, despite mounting anger over joblessness, inequality and corruption.

"People died for this right. They must not waste it," said Nobel peace laureate Desmond Tutu, who has said openly he will not vote for the ANC this time.

The eve of the ballot was marred by some isolated incidents of violence, with police and 1850 troops deployed to several areas to keep order.

In Bekkersdal, near Soweto, some protesters threw rocks at police vehicles and set fire to a polling station, but authorities and election officials said in a statement that the election nationally was "proceeding smoothly".

Casting his ballot in his home village of Nkandla, President Jacob Zuma expressed hope that "all voters will cast their votes without any problems because this is our right, which we fought for."

The 72-year-old president said he expected the "results will be very good," but conceded the election campaign had been "very challenging".

The ANC is expected to win more than 60 per cent of the popular vote, but it is also likely to see its share of the vote slide for a second successive election.

Mr Zuma has been a lightning rod for criticism of the ANC and has been pilloried for the government spending $US23 million ($24.9 million) of taxpayers' money to upgrade his private home.

Throughout the campaign the ANC has relied heavily on past anti-apartheid glories and on the outpouring of grief over the death in December of its former leader Mr Mandela to shore up support.

"Do it for Madiba, Vote ANC!" read one prominent campaign poster, referring to the late statesman's clan name.

For first time voter Nonhlahla, aged 20, that message resonated.

"I am proud that I will be voting for the ANC," she said.

"I am in a free South Africa because of the ANC."

But throughout the campaign, the party's heroic past has collided with South Africa's harsh present, with the ANC unable to assuage anger over a spate of graft scandals, high unemployment and poor basic services.

The election result is not likely to be known before Friday.

AFP