Demonstrators campaigned for Matthias Rath's clinical trials to be judged illegal. Credit: AFP/GETTY

A South African judge has ruled that clinical trials purporting to test the effectiveness of vitamins against AIDS were illegal, and that vitamins should not be advertised as therapies for AIDS.

The ruling covers 12 defendants, including German doctor Matthias Rath and American doctor David Rasnick, a former advisor to President Thabo Mbeki. The pair had been selling vitamin therapies as AIDS treatments, advertising them as effective and saying that anti-retroviral drugs were toxic.

The lawsuit was brought by the South African advocacy group Treatment Action Campaign and the South African Medical Association, which argued that the defendants had violated national regulations covering medicines and related substances.

During the trial the country's health minister, Manto Tshabalala-Msimang, argued that the therapies should not be covered by the regulations as they were not medicines.