The former wife of the country’s first president, Nelson Mandela, was speaking to the BBC as the world marks Mandela Day, which commemorates his birthday.
She told Milton Nkosi that “something is very very wrong… with what we have done”.
President Jacob Zuma has come under increasing pressure to step down from former allies within the ANC.
He has been criticised for his handling of the economy as well as the corruption allegations that he faces.
Mr Zuma will be replaced as ANC leader at the end of the year, but his presidential term comes to an end in 2019.