South Africa has the world's biggest number of people who have HIV/Aids, with more than five million of its 45 million citizens affected. Mr Mbeki's remarks five years ago that poverty, not HIV, was the real cause of Aids earned him many critics, at home and abroad. But the unprecedented attack on him by Zwalenzima Vavi, the general secretary of the powerful Congress of South African Trade Unions (Cosatu), is the first by a senior member of Mr Mbeki's ruling tripartite alliance, comprising the labour movement and the South African Communist Party.
"This lack of government leadership on HIV is a betrayal of our people and our struggle," Mr Vavi said. He added that often Mr Mbeki's controversial Health Minister, Manto Tshabalala-Msimang, spoke about spinach and use of traditional medicines instead of improved access to life-saving drugs. "There is nothing wrong with encouraging our people to eat and live healthily, but it is very wrong when there is silence about the need to ensure people have access to cheap anti-retrovirals," he said.
Mrs Tshabalala-Msimang has often advocated a health diet, including olives and garlic, as a better option to anti-retroviral drugs which she says are toxic and harmful to health. It took a court petition by Aids sufferers in the Treatment Action Campaign (TAC) to get the government to agree on a comprehensive anti-retrovirals programme.
Among the government's failings, Mr Vavi also listed the lack of comprehensive education campaigns, lack of sex education for the young and an underfunded and poorly managed public health system which he said did not adequately tend to Aids sufferers.
Mr Vavi's attack, at the national congress of the TAC, has raised suspicions that a break-up of the ruling alliance is now a matter of time. There have been severe tensions between Mr Mbeki and his alliance partners over the President's reluctance to admit the extent of the Aids problem and his preference of more liberal economic policies and his sacking of the Deputy President, Jacob Zuma, a labour ally, over corruption charges. Such a split would probably see Mr Mbeki and his African National Congress facing real opposition since winning the first all-race elections in 1994.
Mr Mbeki's government reacted angrily to Mr Vavi's attack, dismissing it as being " grossly irresponsible". A government statement said: "At best, the [Vavi] remarks demonstrate a high level of ignorance on the part of the Cosatu leader about the challenge of HIV and Aids in the country and the government response to this challenge."
The government accused Cosatu of allowing its policy to be driven by the Treatment Action Campaign lobby. It said that more than 61,000 people had already begun anti-retroviral treatment in the public health sector and there were now 178 public health facilities providing HIV and Aids related services, including anti-retroviral drugs.