Thousands of children were yesterday tucking into healthier dinners as part of the government's controversial drive to improve standards in school canteens.

Under the guidelines, first published in the spring, traditional favourites such as burger and chips are to be replaced with more fresh fruit, vegetables and fish. They also recommend that every secondary school pupil should be offered cookery lessons from 2008 with an extra £240m earmarked to train cooks, improve facilities and subsidise healthy ingredients.

The education secretary, Alan Johnson, said: "We have already invested heavily to radically transform school food and with today's announcement of extra funding we're taking another big step to ensure parents know pupils will get the nutrients they need during the school day and that school cooks get the kitchens and training they need to deliver healthier food."

But Sarah Teather, the Liberal Democrats' education spokeswoman, said there was little new in the guidelines. "The government are re-announcing what they promised more than 12 months ago and were pestered to do for years before that."

The changes follow recommendations from the School Food Trust, which was set up by the former education secretary Ruth Kelly in the wake of chef Jamie Oliver's television series which highlighted the poor standard of food on offer in schools across the country.

Under the plans pupils will be offered:

· at least two servings of fruit and vegetables a day;

· oily fish at least once every three weeks;

· free fresh drinking water;

· no more than two portions of deep-fried foods a week.

The government also said salt would be banned from school dinner tables, and ketchup and mayonnaise should be available only in sachets.

But John Dunford, general secretary of the Association of School and College Leaders, warned that it should not be left to teachers to improve the nation's diet. "[Schools] cannot turn around years of decline in eating habits without major changes in attitude on the part of parents and the food industry, which continues to direct advertising for unhealthy products at children. We look to the government to show as much energy and commitment for changing parents' attitudes and regulating food industry advertising."

He added that the pledge to offer all children cookery lessons was not properly funded. "The new entitlement to learn to cook comes with no additional resources and places yet more pressure on the curriculum at a time when the government is putting greater emphasis on mathematics, English and science.

"The entitlement to cookery courses does not sit easily with the review of the curriculum for 11- to 14-year-olds now being carried out by the Qualifications and Curriculum Authority, which is widely expected to slim down the curriculum. A leaner curriculum is needed to create space for schools to decide what to teach, not for the government to prescribe additional burdens."

Last night a spokesman for the Department for Education and Skills said: "We want to see a resurgence in the art of cookery. All kids will now get the chance to learn hands-on cookery."