The government has been told to significantly increase its investment in school meals or risk losing its fight against childhood obesity.

In an open letter to secretary of state for children, schools and families Ed Balls, the Food For Life Parternship said the school meals service was at the point of collapse as providers were forced to run at a deficit.

It accused the government of spurning the opportunity to change young people's eating habits because of its reluctance to subsidise healthy, climate-friendly school meals. "The government has the opportunity to use the school meal to influence children's wider eating habits," said Emma Noble, director of the partnership.

Six steps to transforming school food culture with the aim of giving every child access to a healthy school meal by 2015 are proposed by the partnership. They include a 50p contribution per pupil per meal from the government to achieve a £1 ingredient spend and at least 12 hours of cooking lessons a year for every pupil up to key stage 3 by 2011. The package would cost the government £734m should 100% take-up be achieved.

Children's minister Kevin Brennan said the government was investing £650m in school kitchen facilities and dismissed the claim that the school meals system was near collapse. "This is simply not a picture we recognise," he said. "Schools are making massive improvements in a really short period."