Tens of thousands packed a stadium in the scorching central city of Bloemfontein to wrap up weekend celebrations for the African National Congress which Nelson Mandela led to power after the fall of apartheid.

"We will take urgent, practical steps to restore the core values, stamp out factionalism and promote political discipline," Zuma told the crowd to applause and whistles in a more than 90-minute address that largely focused on party history.

He said little about the future of a party that has struggled to stamp out corruption and poverty and is riven by division, in a speech that ended with leaders clinking champagne glasses to a stadium that steadily emptied as storm clouds gathered.

The splashy celebrations have given the party an opportunity to remind the public of its storied legacy, amid deepening frustration at corruption scandals and unfulfilled promises to the poor.

"The ANC mobilised the South African people across the racial, gender and class divide. The ANC, a disciplined force of the left with a bias toward the poor, is also a broad church that is home to all," Zuma told the crowds.

But the event also exposed the party's divisions.

Zuma arrived to loud cheers and song, but also opposition ahead of year-end party elections where some of his erstwhile backers will be pushing for his removal.

One supporter clad in a Zuma T-shirt cheered just a metre away from someone calling for his removal in a "100% Malema" shirt -- a nod to controversial youth leader Julius Malema.

Some in the crowd mimicked the act of showering in a dig at Zuma's 2006 rape trial, in which he was acquitted after testifying he had showered after sex with an HIV-positive woman to lower the risk of infection.

Zuma did not dwell on the party's internal divisions but none of his opponents took to the podium, including the fiery Malema whose arrival sparked roaring cheers and song.

The line-up was seen as a message that Zuma remains in charge.

"Already he has shown that, because there are not any (other) speakers who are going to speak," said youth league member Tefo Labaka, 28, speculating that allowing other speakers would draw attention away from Zuma.

"For now, there is unity because we have to unite for this centenary. But I believe after this event there is going to be a big division," he said.

Malema has styled himself as the voice of South Africa's poor, who are increasingly taking to the streets to demand jobs and better basic services, fueling divisions within a party that wants to represent billionaires as well as paupers.

He was suspended by the party last year for ill-discipline, partly for saying that Zuma's predecessor Thabo Mbeki was a better leader, but remains in office pending an appeal.

The weekend celebratory programme paid homage to the role of religious groups and African traditions, with church services and a ritual animal slaughter.

The events took pains to thank international supporters who sheltered ANC exiles during apartheid and campaigned for the end of white-minority rule.

The programme also showcased the remarkable gains of a party once banned and forced into exile, with a golf tournament Friday where top leaders teed off on a course where they could have been admitted only as caddies just 20 years ago.

In London, British Prime Minister David Cameron on Sunday hailed the ANC.

"It is incredible to see the changes in South Africa that the ANC has helped to bring about," Cameron wrote in a letter to Zuma.

Founded to fight discrimination, the ANC was banned by South Africa's white apartheid rulers in 1960, and its leaders were jailed four years later.

Nearly three decades later, the crumbling regime released Mandela, who oversaw the peaceful transition that paved the way for huge wins in regular polls ever since.

Critics say too many people have been left to make do with shoddy public hospitals and schools, a dangerously high joblessness rate of 25 percent, violent crime and a grim life in shantytowns.