Children should be forced to stay on school grounds at lunchtime in a bid to stop them eating junk food, a Government minister has said.
Education minister Kevin Brennan insisted the restriction could help tackle obesity and prevent tensions with those who live nearby.
The call came as research revealed the extent to which students are leaving school premises and buying food high in fat and sugar.
Academics from London Metropolitan University mapped the movements of hundreds of pupils over a week.
They reportedly found that just 6% ate hot meals, while newsagents, supermarkets and takeaways were far more popular than the school canteen - with 80% using them regularly.
The top 10 purchases included fizzy drinks, chocolate, sweets, chips and fried chicken. Fruit and vegetables came 22nd out of 25 food categories. One chip shop sold 63 portions of chips to pupils within half an hour of lessons ending.
Mr Brennan told the Observer: "Some pupils have a stay-on-site policy for 11-to 16-year-olds, but lets the sixth form go off-site.
"I'm very strongly supportive of that approach. I would like to see more schools operating some sort of stay-on-site policy because its advantages are shown not just in improved uptake (of healthy school lunches) but also improved behaviour and community relationships."
However, headteachers warned that the proposal would often be unworkable.
John Dunford, general secretary of the Association of School and College Leaders, said: "Much as schools would like to keep children on site at lunch time, the number of exits in some - as many as 20 - make this almost impossible."
