Glasgow City Council is offering the electronic incentives to about 30,000 children in 29 secondary schools.

The pupils are given swipecards and can claim various prizes depending on the number of points they gain for eating "sensibly" on school premises.

A council spokeswoman said youngsters "wouldn't turn up their noses at winning an iPod for eating nice food".

They can redeem their points for a selection of goods - from cinema tickets and book tokens to top-of-the-range iPods and Xbox games consoles - at the end of the term.

The council spokeswoman said the scheme, which involves pupils signing up on a voluntary basis, encouraged them to stay within school boundaries at breaks and lunchtimes.

"It means there will be less temptation to go to the chip shop or McDonald's," she said.

"There are a variety of healthy choices on the menu and most pupils wouldn't turn up their noses at winning an iPod for eating nice food."

It would take 100 meals worth 40 points to reach the 4,000 points required for an iPod.

"The most popular thing on the menu is a Vital Mix, which includes soup, a filled pitta, yoghurt and healthy drink like milk, so it's not a case of just lettuce leaves and water," the spokeswoman went on.

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"The reward for the Vital Mix, which costs £1.15, is 40 points, so it would take just 100 of these to get an iPod.

"The swipecard has the pupil's photo on it and the dinner ladies who swipe them obviously know who is who."

The scheme was piloted in three schools in Glasgow at the beginning of last year and is now operating in all of the city's secondary schools.

It will cost the council £40,000 a year - but the local authority said it was a small price to pay if it encouraged children to eat better food which would have a lasting effect on their health.

Steven Purcell, the council's education convener and chairman of the health and diet working group, said he hoped children would be drawn to the scheme.

"We would prefer to incentify the scheme rather than be seen as people who ban things," he said.

"I think we have to recognise that with all the advertising that goes on in schools the habits from early in life around young people the challenge is actually quite hard for us."

And he added: "We have an appalling health record in Glasgow and we need to try anything that will turn that around and make a lasting difference."