The chair of the International Aids Conference has called on the South African Government to make available the drugs which suppress the effects of the HIV virus.

On Friday, former South African President Nelson Mandela is to address the closing session of the conference, which is taking place in Durban.

The conference has been overshadowed by the controversy surrounding President Thabo Mbeki's stance on Aids.

Mr Mbeki's government has refused to make anti-retroviral drugs such as AZT available, despite evidence that these drugs can prevent the transmission of the HIV virus from mother to child.

Hoosen Coovadia, the South African chairman of the conference, said the position was "absolutely clear" regarding the effectiveness of these treatments.

"The government will have to make a decision," Professor Coovadia said.

'Dissidents'

President Mbeki's advisory panel on Aids includes several of the "dissident" scientists who have challenged the general accepted medical view that HIV causes Aids.

Professor Coovadia likened the "dissidents'" denial to saying that "the sun rises in the north."

At the start of the conference, a group of scientists signed the Durban Declaration, stating their commitment to the orthodox view that HIV is indeed the cause of Aids.

"The importance of this document cannot be underestimated," Professor Coovadia said.

Mandela's call

Mr Mandela is expected to urge people working in the field of Aids research to redouble their efforts to find a cure.

The six-day conference has highlighted the extent of the problem in Africa, where nearly 25m people are HIV positive or have Aids.

But only a tiny fraction of African sufferers have access to expensive drugs that can suppress the virus.

The next international Aids forum will be held in Spain in 2002.