South African police say they have foiled a plot by suspected right-wing Afrikaners targeting an African National Congress (ANC) conference attended by President Jacob Zuma and dozens of senior government officials.
Four men aged between 40 and 50 were arrested on Sunday. A police spokesman said on Monday that there was evidence they were planning acts around the country and not just at the ANC meeting in the central city of Bloemfontein.
The majority of South Africa's whites accepted the ANC's victory in the 1994 election that brought Nelson Mandela to power and ended decades of white-minority rule. However, a tiny handful continues to oppose the historic settlement.
"Their acts are widespread. We arrested them in different provinces," said spokesman Billy Jones.
ANC spokesman Keith Khoza said preliminary information suggested the men were planning to bomb the marquee where Zuma and 4,500 delegates are holding a five-day meeting to choose the ANC's leadership for the next five years.
"This would have been an act of terrorism that South Africa can ill afford," Khoza said.
The Federal Freedom Party (FFP), a fringe group fighting for self-determination for the white Afrikaner minority, confirmed two of those arrested were FFP members but denied any role in the suspected plot.
In July, a former university lecturer was found guilty of orchestrating a 2002 plot to overthrow the ANC and assassinate
Mandela - now 94 and recuperating in a Pretoria hospital after a successful surgery to remove gallstone.
There was a heavy security presence at the Bloemfontein meeting and the few vehicles being allowed onto the university campus hosting the event were being searched by police and sniffer dogs, as political killings have been on the rise in South Africa in recent years.
Dozens of people have been murdered in the last two years, with most of the violence concentrated in Kwazulu-Natal province. It is feared there could be more violence ahead of the ruling party's conference in December.
Members of the ANC have been particularly targeted in recent months.
The conference is set to give Zuma a second mandate to lead the party and - given the ANC's dominance at the ballot box - another five-year term in 2014 as president of Africa's biggest economy.
Zuma's nomination for the post of party leader was met by wild cheers from delegates, in marked contrast to the muted applause and occasional whistle that greeted his only challenger, Deputy President Kgalema Motlanthe.
Motlanthe withdrew from the race to become Zuma's number two, virtually handing the position to former union leader Cyril Ramaphosa, South Africa's second-richest black businessman who is returning to politics after a decade absence.