These shocking findings were published in a human rights report of the United Nations on Wednesday.
"We are deeply concerned over the situation where children are forced to sell their bodies to survive," Lyn Perry, director of the Johannesburg Child Protection Association, said.
The report claimed that children were abducted from Angola, Mozambique, Kenya, Ethiopia, Uganda and Eastern Europe or were lured to the streets of Johannesburg or Cape Town with false promises.
Angolan, Congolese and Nigerian syndicates apparently transported the children, but Russians and Chinese are seemingly also involved.
UN officials, who investigated child abuse, child rape and prostitution in South Africa last year, compiled the report.
They said the remnants of apartheid, poverty and hunger played a significant role in most of the crimes against children.
The food shortage in South Africa's neighbouring countries is compounding the problem.
The South African Human Rights Commission found last year that a third of the country's children were sexually abused.
The lack of a social framework to protect children was given as the cause of this situation.