By Nick Miles BBC, Cape Town

The Treatment Action Campaign wants more Aids drugs available

South Africa has one of the highest rates of infection in the world, with one in five adults affected.

This makes five million people in all who are HIV positive.

In spite of the spread of the virus it was only two years ago that the government began to make anti-retroviral drugs widely available.

Resignation call

More than 3,000 researchers, activists and politicians will be at the four-day conference in Durban on South Africa's east coast, which begins at 0800GMT.

They will be discussing the spread of the virus and the latest HIV vaccine trials.

TAC has called on Ms Tshabalala (r) to resign

But those debates are likely to be overshadowed by the ongoing row between the health minister, Manto Tshabalala Msimang, who is speaking at the start of the conference and groups lobbying for more anti-retroviral drugs to be made available.

One of those groups, the Treatment Action Campaign, is calling on Mrs Tshabalala to resign because she has promoted a diet high in foods like lemons and garlic as a natural treatment for people with HIV, at the same time as stressing the side effects of anti-retroviral drugs.

She said she does not want to take sides in the debate but Aids activists say that is irresponsible.

They want an unequivocal statement from her that anti-retrovirals are the most effective treatment for HIV.

In the past the South African government was sceptical about the link between HIV and Aids and it questioned the cost effectiveness of anti-retrovirals.

Two years ago during South Africa's first HIV conference, President Thabo Mbeki's government faced legal action from HIV activists to provide free HIV drugs.