Police spokesperson Andre Beetge said police had received information that syndicates were targeting children in nightclubs and entertainment areas in the run-up to the event, which starts on June 11.
"We have received information that human trafficking syndicates are increasing their efforts to get their hands on children, and not only girls, but boys too," Beetge said.
"Parents should be aware of this threat and take better control over the movement of their children outside of the protected environments of their homes and outside of adult supervised premises such as schools."
Beetge said the modus operandi used by the syndicates was to capture children in areas where the least amount of attention would be drawn from onlookers.
"They prefer to target children that come from broken family circumstances, where the children are falsely promised wealth, jobs and a better future by the syndicates.
"Usual places are night clubs and other entertainment centres where children and teenagers 'hang out'," he said.
Once kidnapped, the children are injected with drugs to keep them from screaming, and once at a "safe house" are repeatedly gang raped for periods of up to two weeks.
"They are then taught that drugs will be supplied if sexual acts are performed and used as prostitutes on the streets," Beetge said.
Beetge's warning comes after sex work researchers dismissed fears of a massive rise in human trafficking for the World Cup.
Marlize Richter, a researcher from the University of the Witwatersrand said at a discussion hosted by the Institute for Security Studies (ISS) in Cape Town on Monday night that fears of human trafficking had been grossly exaggerated in the build-up to the tournament.
"I suspect very little of it is done maliciously. The World Cup provides the opportunity to raise awareness of levels of violence in South Africa, specifically on women and children.
"I don't think that makes it right to perpetuate myths and unsubstantiated claims.
"I think there is an element of resources in the NGO world and if you can show there is a big threat and that your organisation can provide for it, then it is in your interests to perhaps spice things up," she said.
Chandre Gould, a researcher for the ISS who has authored a book on sex work in Cape Town - Sex Work and Human Trafficking in a South African City - said she had encountered very few cases of human trafficking in her investigations.
She said a widely reported figure of 40 000 sex workers being trafficked into South Africa for the tournament was entirely false.
"That number of 40 000 has no basis in fact. In the World Cup in Germany and the Olympics in Athens no increase in trafficking was found. There is no reason to believe South Africa will be any different from Germany or Athens.
She said very little research had been done on human trafficking. In Cape Town she found only a handful of cases of women who had been trafficked.
"We determined a point-in-time estimate of the number of sex workers - 964 in brothels and 245 on the street - a total of 1209. This means that 0.03% of the population of Cape Town works in the industry.
"Our evidence suggests that while sex workers are often subject to exploitative or abusive working conditions, very few are forced to sell sex. Most take up the work because it is a rational choice given its earning potential," Gould said.