England's new academy schools are being urged to commit to serving healthy food to pupils.
The School Food Trust, is to write to all 1400 academies asking them to confirm their adherence to national school meal nutrition standards.
Last month TV chef, Jamie Oliver, voiced concerns that food quality was slipping in academies which are not subject to the regulations.
The rules were brought in six years ago after a campaign by the chef.
The names of academies which pledge to follow the national standards for healthy school meals will be published on the School Food Trust website.
The trust will use the data in a report to government on meals in the state-funded but privately run schools due to be published by March.
In the letter trust chief executive, Judy Hargadon, writes: "You may be aware of recent questions raised by campaigners about the commitment of academies to the national school food standards... We are seeking to clarify the situation."
Lynda Mitchell, chair of the Local Authority Catering Association, which has campaigned closely with Jamie Oliver, welcomed the trust's new focus on meals in academies but said she would prefer one single standard applicable to all schools.
She said: "There is the potential for a huge gulf. I think a two tier system takes away parents' confidence that their children are being well fed at school.
"It leaves schools able to hide behind their academy status and avoid signing up to the standards.
"What an academy bursar or head my determine to be healthy food may not actually adhere to proper nutrition standards because people's ideas on healthy food are not of one accord."
Children's food campaign coordinator Christine Haigh also said government should require all schools to meet the standards.
She said: "The fact that the school food standards, which ensure that children are served healthy food at school, no longer apply to academies and free schools is a scandal.
"Already there is evidence that standards are slipping, risking a return to the grim days of turkey twizzlers for the million children who now attend academies."
The move was welcomed by a group representing academies.
Andy Schofield, principal of the Wellington Academy and chair of The Schools Network's academies steering group, said: "Academies have long recognised the importance of a healthy diet, alongside participation in sports and emotional wellbeing to ensure young people are healthy and engaged in their education.
"The raison d'etre of the academies programme is to allow schools to look at the child as a whole and to cater for all their needs."