ACT has labelled food rules for early childhood centres an "absurd overreach" that should be scrapped.
It was announced last year that new criteria was being introduced to early childhood centres to reduce the risk of children choking.
An example for one to three-year-olds included the directive that hard fruit and vegetables such as apples and carrots should be cooked or grated if raw, and bread should be cut to a size a toddler can easily hold and eat.
For children under five, the Ministry of Health guidelines used the example that grapes, berries and cherry tomatoes can be quartered or chopped smaller to reduce the risk of choking and raisins and sultanas could be soaked to soften and cut in half if large.
The party's education spokesperson Chris Baillie said it was "crossing the boundary of reasonable expectation and personal responsibility and tying people up in red tape".
"No matter how worthy the intention of the rules is, it will undoubtedly start to impact what ECEs say parents can send in their children’s lunchboxes."
The Early Childhood Council CEO Peter Reynolds said centres managed "a range of abilities around food safety every day, and we believe guidelines are the right approach, not blanket rules".
Last year, Ministry of Education's Katrina Casey said early learning services were "encouraged to follow the Ministry of Health (MoH) guidance on the provision of food".
"Now it will be compulsory."
"Food choices must also meet the nutritional and developmental needs of each child," Casey said.
From next Monday, children must be seated and supervised while they eat, and centres that provide food must adhere to MoH guidance or promote guidance to parents if food is brought in.
In a letter sent to early learning centres on Wednesday, Casey stressed the MoH Guidance "does not automatically apply to food parents provide".
"Where services can show they have promoted the MoH Guidance to their parent community, and are following other related licensing criteria including ensuring children are seated and supervised when eating, they will have met their obligations in relation to these requirements.
"It is your choice as to whether you want to have a food policy for parents that matches the requirements – but you are not required to do so."
From April 8, an adult with a current first aid certificate must be present to supervise up to 25 children eating - that was down from 50.