A South African court has banned a team of scientists and doctors, including a former adviser to President Thabo Mbeki, from conducting unauthorised clinical trials into the use of vitamin therapies to treat Aids.

German doctor Matthias Rath and American biochemist David Rasnick, who used to sit on Mbeki's Aids advisory council, were among 12 people accused in the Cape high court of supervising illegal medical trials in black townships and selling unregistered vitamin supplements to poor Aids sufferers. The suit was brought by the South African Medical Association and the Treatment Action Campaign lobby group, which said some of Rath's patients died after relying on his unproven remedies rather than seeking conventional treatment at state-run clinics.

Judge Dumisani Zondi yesterday ruled against Rath and Rasnick, who is a member of the Dr Rath Health Foundation. "It is declared that the clinical trials conducted in South Africa ... are unlawful," Zondi said.

Rath was also barred from publishing any advertisements for his natural Aids remedies - high-dose vitamin pills containing minerals such as iron and iodine - which he claims are more effective that antiretroviral drugs. His theories have proved hugely controversial in South Africa, which has one of the highest incidences of HIV in the world, with up to 1,000 people dying of Aids-related illnesses every day.

Aids activists say that Rath found a market for his products because of mixed messages from the government, which was slow to acknowledge the scale of the HIV problem and to distribute life-saving drugs. Mbeki flirted with dissident theories on Aids treatment for years, while the health minister, Manto Tshabalala-Msimang, publicly advocated the use of beetroot, garlic, lemons and African potatoes rather than clinical drugs.

As part of the suit, the South African government was accused of failing in its statutory duty of care for the public by failing to prevent Rath from distributing his products. Appearing before the court, Tshabalala-Msimang said that Rath's remedies were not medicines but foodstuffs, and thus fell outside the Medicines Control Council's regulatory scope.

But Zondi ruled that Tshabalala-Msimang, who had opposed the suit, must now take reasonable measures to prevent Rath from conducting further trials and advertising his products, especially Vitacell, which he says has strong anti-Aids benefits.

Rath, who was not in court to hear the ruling, claimed the lawsuit was an example of "pharmaceutical colonialism" which had "genocidal consequences for the people in the developing world".

The Treatment Action Campaign welcomed the decision. "This judgment this morning is a victory for the rule of law and the scientific governance of medicine," said Nathan Geffen, the group's spokesman.