Children will be served at least two portions of fruit or vegetables in school lunches and get deep-fried items such as chips no more than twice a week under nutrition standards published by the government on Friday.

From September school meals in England must be free from low quality meat products, fizzy drinks, crisps, and chocolates. Also banned is the sale of junk food in school tuck shops and vending machines.

Instead, high quality meat, chicken or oily fish must be offered on a regular basis.

“This is a really ambitious programme,” Schools Minister Jim Knight told BBC radio. “It will take a long time to transform a whole culture around food and transform the health content of school meals, undoing decades of neglect.”

The minimum nutrition standards come as part of a 220 million pound programme announced March last year by then Education Secretary Ruth Kelly to improve school meals.

Her pledge followed a public outcry over the quality of food served to schoolchildren led by television chef Jamie Oliver.

The extra money is to cover the cost of better ingredients as well as training for school kitchen staff.

But some fear too strict a ban on junk food may backfire.

“If you start imposing something like this, children will either vote with their feet, go home or visit the local chip shop,” Mick Brookes, general secretary of the National Association of Head Teachers told the BBC.