Many South African children whose parents have died in the Aids epidemic are neglected, starving and ill, and some are turning to prostitution to survive, according to a report by the Nelson Mandela Children's Fund.
A study of 20 townships and villages showed that many communities did not even know that Aids orphans were living in their midst.
"The level of deprivation in respect of basic needs was so deeply felt that many children shed tears," the report said. "Even as we spoke to them, a good number of these children, some as young as four to five years old, had gone days without food."
Officially South Africa has the greatest number of HIV-positive people in the world - 4.7m, or one in nine of the population. About 700,000 children have been orphaned by Aids, and around half of those are thought to be HIV-positive.
Mr Alf Nghalaluma, who directed the research, said the traditional way of caring for such children was falling apart.
"While the extended family institution remains strong and continues to absorb orphans, it's beginning to cave in because of a number of circumstances, the number of people dying and leaving orphans behind. They cannot cope with the numbers," he said.
"In the East Rand, six children stayed alone for almost 18 months," said Mr Lungi Mabude, a researcher. "At the stage they were discovered they were almost dying and did not even want to go with the ambulance."
In the town of Melmoth, 100 miles north of Durban, researchers discovered that 10% of Aids orphans lived in households headed by other children. The biggest problem for many was finding food. Some orphans went to church hoping to beg the pastor for something to eat.
The report said the Aids orphans were generally more interested in school than other children, because they saw it as a means of escaping poverty, but sometimes they were turned away because they had no money for fees or uniforms.
"One of their key problems, which cuts very deep, relates to stigmatisation of the children when their friends or teachers get to know [that their parents died of Aids]," Mr Nghalaluma said.
The report quotes children's accounts of the discrimination they suffer.
"Friends to my younger brothers do not play with them any more, they tell them they are suffering from Aids. My teacher said I will also die of Aids," one said.
Some children were also vulnerable to violence and sexual abuse. "It is fairly common that children have been forced into prostitution to feed themselves and their families," said Ms Irene Menell, a trustee of the Nelson Mandela Children's Fund.
The study concluded that there was "an enormous need for crisis intervention as well as long term development strategies".
"The number of orphans will escalate at a very rapid rate. The numbers are so overwhelming that the community is beginning to fail to cope with the problem," Mr Nghalaluma said.
The International Labour Organisation, which brings together governments, unions and employers, announced yesterday that it had drawn up a new code to protect the job rights of Aids sufferers.
The code, the first effort to formulate a policy for dealing with HIV in the workplace, will be presented to the UN special assembly on Aids in New York next week. Although it is not binding in law, officials said the code would send out a strong message to the ILO's 191 member countries.
The special session of the UN General Assembly next week provides the setting for what one senior UN official called an unnecessary culture war over the moral implications of the fight against Aids. Disagreement over references to homosexuals, sex workers, drug users and prison inmates has stymied work since last month on a declaration which the three-day session is due to adopt.
Human Rights Watch (HRW) accused a coalition of Muslim and Catholic states of "moral squeamishness".