It was the interview that broke the taboo of criticising a living legend. Winnie Madikizela-Mandela had delivered a withering verdict on her former husband Nelson, saying the South African anti-apartheid hero adopted by the world had "let us down". Yesterday she said the whole thing had been "fabricated" and launched a scathing attack on the wife of V S Naipaul, the woman she blames for tarnishing her name.

"I would like to state categorically: I did not give Mrs Naipaul an interview," she said in a statement. "I will in the coming days deal with what I see as an inexplicable attempt to undermine the unity of my family, the legacy of Nelson Mandela and the high regard with which the name Mandela is held here and across the globe."

Nadira Naipaul had recounted the pair's conversation in the Evening Standard this week, describing how Mrs Madikizela-Mandela had castigated her ex-husband for not doing enough to loosen the white stranglehold on the South Africa economy and improve life for its previously-persecuted black population, and for accepting the Nobel Peace Prize alongside apartheid-enforcer President F W de Klerk.

The London newspaper, which published the piece on Tuesday, was standing by its story last night. "We cannot understand Winnie Mandela's denial of an event and conversation which clearly took place," it said, noting a photograph of her standing next to the Naipauls had been published alongside the story.

The circumstances surrounding the two women's tête-a-tête are clearly contested. However, Mrs Madikizela-Mandela did not, in her statement, specifically deny uttering any of the remarks. And while her purported criticisms triggered condemnation, there were many commentators and ordinary South Africans who detected kernels of truth.

"There isn't much ... that most South Africans will not have thought at one time or another. And the subject of Mandela is not holy ground," the South African daily, Business Day, said in an editorial.

Mrs Madikizela-Mandela was Nelson's second wife. While Mr Mandela spent his 27 years in jail, the apartheid regime made his wife the target for a campaign of harassment. The image of Mrs Mandela holding her husband's hand aloft on that triumphant February day in 1990 when he walked free is etched on the world's memory. Six years later, following her infidelity and convictions for kidnap and fraud, the couple were divorced. Today, she is a member of the ANC's national executive committee.

Mcebisi Ndletyana, a member of the Human Sciences Research Council, said this week's furore had highlighted Mrs Madikizela-Mandela's dual role as a senior and longtime ANC figure and one of its vocal critics. "It's vintage Madikizela-Mandela – this is the role she has assumed within the organisation, of saying uncomfortable things."

Disillusionment with the ANC is growing in South Africa. Protests over living conditions are mushrooming, posing an increasing political and security headache for President Jacob Zuma, with just 90 days to go before South Africa hosts the World Cup. This week around 1,000 township residents, demanding better schools, housing and sewage systems, barricaded roads in Soweto leading to the venue for the opening and final game.

Poorer South Africans are angry at the money being lavished on a one-off football tournament, and feel that the boomtime of Africa's largest economy has been largely enjoyed by white South Africans and not the black majority. Some blame Nelson Mandela for missing a window of opportunity when hammering out a deal in the 1990s; others blame his presidential successors.

"Die-hard supporters are questioning not only the Zuma presidency but the whole of the ANC's governing record," explained political analyst William Gumede. "The ANC is having so many crises now, day after day. And this latest episode with Winnie plays into the sentiment that people are starting to feel aggrieved. People who voted for ANC last year are getting despondent."