Imperial Crown Trading (ICT), the company's lawyer Ronnie Mendelow, and their counsel Edmond Wessels were also in the firing line.
"The makers of those allegations will regret those allegations through their cheque books," Hellens reportedly told the Star newspaper.
"They said I had an unnaturally close relationship with her. That suggested that I had an affair with her. I have never had an affair with Glynnis. I have known her for probably 25 years."
According to the Star, the National Prosecuting Authority (NPA) said Breytenbach had failed to act impartially when investigating the Kumba Iron Ore/Sishen and ICT mining rights issue.
Hellens represented Sishen.
In his October 2011 complaint to the NPA, Mendelow claimed that Breytenbach had "engaged" Sishen's legal counsel, Hellens, in drafting various affidavits.
The NPA accused Breytenbach of abusing her authority as a prosecutor. She was acquitted on Monday after a lengthy disciplinary hearing.
The NPA said the inquiry's findings were "factually incorrect and legally unsustainable" and it would ask the court to review them, the Star reported. – Sapa