The police say there have been 21,000 cases of child rape or assault reported in the past year, mostly committed by male relatives of the victims.

The figure had risen sharply in the past 10 years, they added.

The Northern Cape minister of health, Dipuo Peters, said: "I suspect that at least part of the reason these children were raped is because of the myth held in rural areas by men with HIV that they can cleanse themselves by having sex with a virgin.

"I do a lot of Aids education; this myth is firmly entrenched and we are doing our best to dispel it."

In other cases, she said, children are raped because they are unlikely to carry the virus. But many of those assaulted ended up infected, so that rape became, in effect, a death sentence.

"I think it's very gruesome," she said. "We need to punish the perpetrators. They are really cruel."

She was speaking after visiting two recent victims in a hospital in Kimberly. One is a nine-month-old baby who has already undergone extensive surgery and faces several more operations.

Six men, aged between 24 and 66, have been charged with raping her after she was left unattended by her teenage mother.

The second, a three-year-old, was allegedly raped by her grandfather three days earlier. She has had to wait several days for an operation because there was no gynaecologist available.

On Tuesday a 14-month-old girl from the Free State was raped, allegedly by two uncles in whose charge she had been left by her mother. The men, aged 34 and 37, have been remanded in custody.

The next day a four-year-old from Venda died in hospital three months after she was allegedly raped by her 35-year-old father. He has been charged with murder.

Yesterday the women's league of the African National Congress called for life sentences for HIV-positive men who rape children.