Chipping children is being advocated in the US as a way of preventing parents from losing their kids.

The idea has come from US company Applied Digital Solutions (ADS), which argues that implanting chips with Global Positioning Satellite (GPS) technology could be used to find lost children.

The company says the device, which is the size of a wristwatch-face and could eventually be made even smaller, could be used to find kidnapped children, locate young kids who wander away from parents and track teens who participate in risky behaviour.

ADS spokesman Matthew Cossolotto said: "With an implanted device, the child doesn't have to remember to wear it. It can't be lost or stolen or stripped away. And it's totally concealed."

The company is set to launch a prototype later this year. In the meantime, ADS already manufactures two similar products: VeriChip and Digital Angel.

The plan has the backing of the host of TV crime programme America's Most Wanted, John Walsh, whose six-year-old son was kidnapped and killed in 1981.

Speaking recently on the TV show Larry King Live, Walsh said the chip could be used to locate kidnapped or missing children. In a worst-case scenario it could even serve to find a missing child's body.

But the chipping idea is less popular with parental groups, who think it better to teach children to monitor their own behaviour rather than trying to keep track of them 24 hours a day.