Parents can now monitor what their children eat in school thanks to an electronic payment system being hailed as a new weapon in the fight against spiralling student obesity.

The system was introduced by Cobb County and Marietta City, two education authorities in Atlanta, Georgia, last month. It automatically downloads details of items students purchase from the school cafeteria to a website.

“Parents appreciate the opportunity to know exactly what their children are buying,” said Bill Doughty, a spokesman for Marietta City Schools. “They can see if they’ve ordered fruit or a cookie.”

The tracking function is an extension of a system used by 60 US education authorities that allows parents to set up special accounts from which students pay for their school dinners, rather than giving them cash.

Its aim is to prevent students buying junk food outside school, Mr Doughty said.

Students enter a personal identification number at the cash register in the school cafeteria to charge meals to the account.

Parents log on to a website using a username and password, then call up their child’s information by inputting a student identification number, said Tina Bennett, director of Atlanta, Georgia-based manufacturer Horizon Software International.

“There are some concerns that we shouldn’t be offering less-healthy options at all,” said Mr Doughty. “But it doesn’t do us any good to provide meals that do not get purchased.”

Marietta schools offer reduced-fat burgers and pizzas and low-sugar ketchup alongside fruit and salad, nutrition director Sandy Laffan said.