Five activists protesting against discussions on nuclear energy were "roughed up" at the Industrial Development Corporation (IDC) office in Sandton Greenpeace Africa says.

The environmental group staged the protest in an attempt to halt talks aimed at expanding nuclear energy on the continent, spokeswoman Ferrial Adam said in a statement.

"Five Greenpeace activists have been roughed up outside the Industrial Development Corporation building in Sandton... following their action this morning where they demanded a halt to discussions aimed at expanding nuclear not only in South Africa, but also the rest of the African continent."

Energy Minister Dipuo Peters opened the conference, which was organised by Omega Investment Research, a Cape Town-based international advisory firm.

Police could not immediately confirm the incident.

flickr video: Security Guards Pillow Fight at Greenpeace Protest