Notable absentees at rally mark crisis at the heart of the ANC

In Long Walk to Freedom, Nelson Mandela describes a recurring nightmare during his 27 years of sleeping in prison cells: To be released from jail only to find no one waiting for him.

Yesterday, as the African National Congress marked 20 years since his release from Victor Verster prison, the absentee list at a commemoration at the jail provided evidence that political friction is imperiling Mandela's legacy.

Under the scorching Western Cape sun – which prison guards described as weather identical to 11 February 1990 – Winnie Madikizela-Mandela was due to recreate the historic walk she had taken through the prison gates two decades ago holding her husband's hand.

But hundreds of ANC supporters bussed in to attend the event were disappointed. Ms Madikizela-Mandela, who is hugely popular with ordinary South Africans, did not turn up. Neither did President Jacob Zuma to whom the ANC had given top billing at a mini rally.

The 20th anniversary came as the ANC government is facing its worst internal crisis since the end of apartheid in 1994. Polygamist President Zuma, who last month married for the fifth time, has been ducking "Babygate" after revelations that he fathered his 20th child, but not by one of his official wives.

As the excesses of Mr Zuma's private life have spilled into the public domain, gloves have come off inside the ANC revealing the depth of the rift between the leftwing – which supported Mr Zuma's ascent to power – and the market-friendly wing that governed the country after Mr Mandela became president in 1994. In the past week, new protests against the government's lack of success in tackling poverty have erupted in the Siyathemba township in Balfour, Mpumalanga.

An ANC spokesman, Jackson Mthembu, said he was "not in a position" to comment on Ms Madikizela-Mandela's non-appearance. Calls to her office were greeted with requests to "call back on Monday'' while some outlets quoted unnamed sources as saying returning to the prison was "too painful'" for Mr Mandela's ex-wife.

Mr Mthembu said: "President Zuma would have loved to address the rally at the prison but it just did not work out that way, for logistical reasons, because he ran out of time."

A woman in the crowd said the ANC was "just too ashamed" of Mr Zuma to allow him to address ordinary people. Another saw the absence of Ms Madikizela-Mandela as a move by the party to prevent her from speaking out against Mr Zuma. A student electrician Richard Ndogeni, 25, said: "The politicians of today are just eating the money. They are not doing their jobs. They only care about cars and houses, not the people."