The Green Party says official papers show the Government failed to consult schools or the Ministry of Health before scrapping school food guidelines in February.
The guidelines had instructed schools to make only healthy food available.
Green Party health spokesperson Sue Kedgley says papers obtained under the Official Information Act show the Government ordered only one report from the Ministry of Education before scrapping the guidelines.
The papers show the Education Ministry warned the minister that Maori and Pacific students would be adversely affected.
Ms Kedgley says the party's annual school food survey found 84% of schools sell pies, sausage rolls and hot dogs - an increase of 14% on last year - which shows the Government needs to reinstate the guidelines.
Education Minister Anne Tolley says she consulted with the education sector, which sent a clear message it wanted requirements to sell only healthy food and drink removed.