A South African court has ordered a German doctor to stop publishing statements critical of the country's leading Aids campaign group.
TAC has campaigned for ARV drugs to be given to the HIV positive
Dr Mattias Rath accused the Treatment Action Campaign of being funded by international drugs firms to help sell their products in South Africa.
The Cape Town high court rejected Dr Rath's argument that his claim was part of a necessary debate on HIV/Aids.
The Rath Foundation says its vitamin supplements can help stop Aids.
TAC has been at the forefront of pressure on the South African government to give anti-retroviral drugs to all those who need them.
South Africa has more than 5m people who are HIV positive - among the world's worst affected countries.
Judge Siraj Desai said the order should not prevent a free debate about Aids but would restrict the methods used by Dr Rath.
He has taken out full-page adverts in the International Herald Tribune and the New York Times, saying the drugs are a form of genocide.
He has placed similar adverts in South Africa, where the government has been accused of not doing enough to help those with HIV/Aids.
Dr Rath says that ARVs - generally seen as the most effective treatment for HIV/Aids - are toxic.
A TAC spokesperson accused Dr Rath of exploiting vulnerable people to promote his own multi-vitamin products.
The group has said it intends to bring a full-scale defamation action at a later date.
Health Minister Manto Tshabalala-Msimang has also warned of the negative side-effects of the "cocktail therapies" and insisted on the importance of a good diet - including raw garlic, lemon, olive oil and beetroot - to fight HIV.
A joint statement from the World Health Organization, the UN children's fund Unicef and UNAids has described Dr Rath's adverts as dangerous and unhelpful.
Some Aids workers in South Africa say that some people have stopped using ARVs following Dr Rath's public campaigns.
Dr Rath has long advocated the health benefits of vitamins, in conditions as diverse as cancer, heart failure and osteoporosis.
The profits from his vitamin marketing company go to support his health foundation.