By Imogen Foulkes
BBC News, Geneva
South Africa is in danger of losing the battle against HIV/Aids, the United Nations children's agency has warned.
South Africa has an estimated 1.5 million Aids orphans
Unicef's South Africa representative, Macharia Kamau, said infection and death rates were outpacing treatment.
This was having a devastating effect on children whose parents died of Aids, and sent out a dire message for the future, he said.
Mr Kamau said if present trends continued, there could be five million orphans in South Africa by 2015.
South Africa is one of just nine countries worldwide where infant mortality is rising - from 60 deaths per 1,000 births in 1990, to 95 deaths today.
The main reason, Unicef says, is HIV/Aids.
About 12% of the population is living with HIV, but among pregnant women presenting at antenatal clinics it is 30%, rising to nearly 50% in some regions.
Speaking in Geneva, Mr Kamau said the effect on children was devastating, and that infants whose mothers died of Aids were at huge risk of dying themselves.
Older children who have lost one or more parents faced a struggle to survive and to go to school, he added.
In South Africa today there are 1.5 million Aids orphans. If the trend of 400,000 deaths from Aids per year continues, by 2015, the number of orphans will have reached five million.
Mr Kamau said that the numbers of people in South Africa being treated for Aids were constantly being outstripped by the numbers becoming infected and dying.
He described this as a dire message for the future because although 380,000 South African Aids patients were receiving anti-retroviral drugs, 1.2 million were not receiving treatment.
As long as infection and death rates continued to outpace treatment, South Africa would lose the battle against Aids, he said.
Unicef says an aggressive expansion of treatment is needed immediately, alongside a much more open Aids prevention campaign from the government, to challenge the stigma which still surrounds the disease in South Africa.