JOHANNESBURG (AFP) - South Africans have voted resoundingly to extend the ANC's 20-year rule, ignoring leadership scandals and economic malaise in a wholesale display of loyalty to the party once led by Nelson Mandela.

Final results were expected on Friday, but with about 95 per cent of the ballots counted, the ANC had garnered a thumping 62.5 per cent of the popular vote, spelling a parliamentary majority big enough to hand embattled President Jacob Zuma a second five-year term.

ANC spokesman Jackson Mthembu said the 102-year-old party - which has held power since helping to end apartheid in 1994 - would ultimately receive "an overwhelming mandate" from voters.

The ANC's status as the party of liberation was drilled home by the recent 20th anniversary of democracy and the outpouring of emotion that accompanied the death of former president Mandela in December.

But with 62.5 per cent, it would still fall short of the two-thirds majority needed to amend the constitution and will see its winning margin reduced for a second consecutive election, down from 66 per cent at the last poll.

Meanwhile the main opposition party, the centrist Democratic Alliance, made rapid gains, boosted by a strong urban turnout.

Its share of the vote rose to 22 per cent, up from 17 per cent at the last election in 2009, according to the incomplete results, and looked set to top the polls in Johannesburg and Cape Town.

Julius Malema's populist Economic Freedom Fighters gained 6.1 per cent of the vote, less than a year after the party was formed. It garnered more than one million votes.

Both DA and EFF support has been bolstered by a series of scandals surrounding Zuma and frustration at rampant poverty and poor public services.