This week she took to Facebook, on which she claims close to 5 000 "friends", to launch a blistering attack on a former head of the World Bank, Mamphela Ramphele, calling her a "mistress" and even suggesting that she had no right to speak on behalf of Steve Biko's family.

On Monday, Ndabeni wrote on the social networking site: "I wonder why does the Biko family allow his mistress Dr Ramphele to speak on behalf of Biko whilst his wife is alive? Where I come from Mistresses are not allowed to speak in public about their lovers."

Ramphele had a son by the late Black Consciousness Movement leader. Ramphele has been scathing of the government's failures in critical areas such as education.

Ndabeni first posted a link to Ramphele's biography, written by Bonnie Leib. She followed up with the controversial post, which had garnered 57 comments and 54 "likes" by yesterday.

Asked for comment, Ndabeni said she was "Googling women in politics" when she stumbled on Ramphele's biography.

"I shared that thing with my Facebook friends. When you want to make it a public info, I can't be involved in that," said Ndabeni.

"So you will do what you do when you take other people's business and make them public."

Vuyiseka Dubula, general secretary of the Treatment Action Campaign, commented: "Hayibo, Stella, that's too judgemental sisi, when it comes to Biko and women I wouldn't have such strong views about Mamphela. She also has a right to speak about her lover who was well known to be her lover too even the wife was aware. Anyway that's my view."

But former chairman of the parliamentary portfolio committee on public enterprises, Vytjie Mentor, was more hard-hitting.

"He he he, well put comrade Stella Ndabeni Abrahams. Mistress in English means a girl friend or lover of a married man. This is an honest account of what Dr Mamphela Ramphele was to the Icon Steve Biko. Sometimes the truth hurts, sometimes culture is used to cover the truth."

It is not the first time Ndabeni has courted controversy. In July she slated Winnie Madikizela-Mandela on Facebook for publicly criticising President Jacob Zuma's multiple marriages.

"Life can be interesting. Dali Mpofu represented Julius Malema in the national disciplinary committee hearings. Mam' Winnie has always seen a great leader like Madiba in Malema, and now the mother of our nation sees immorality in Zuma. Who is a saint between the two of them?" Ndabeni wrote.