"My client has filed a case of crimen injuria and defamation of character," Ndabeni's lawyer, Makhetha Matumba, said.

The letter surfaced a few days after Ndabeni responded on a private Facebook page to Winnie Madikizela-Mandela's public criticism of President Jacob Zuma's polygamous lifestyle.

Ndabeni wrote: "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?"

Her post was interpreted as referring to Madikizela-Mandela's alleged personal relationship with Mpofu years ago.

ANC Youth League spokeswoman Magdaline Moonsamy wrote an open letter to Ndabeni lambasting her for attacking Madikizela-Mandela.

A second letter attacking Ndabeni, and dragging her family and a senior government official into the drama, emerged.

The letter warned Ndabeni to refrain from airing "other people's dirty linen" if she did not want her own skeletons to be let out of the closet.

When some of the listed authors were contacted, two acknowledged knowing about the letter but distanced themselves from it.

Two others said they were aware of the letter and its contents, and admitted to being involved in its writing.

Ndabeni referred all questions to Matumba, who said he was investigating the matter.

"I have phoned all the people who are [named] in the letter, " he said.

The former chairman of the National Youth Development Agency, Andile Lungisa, said: "Young women cannot be publicly fighting each other. They are supposed to embrace and support Stella as a young woman who has achieved so much."