Consumers are not being given full information on food labels about whether the product they are buying has been processed with genetically modified organisms, the Green Party says.
New Zealand imports 57 varieties of genetically modified foods.
Food does not have to be labelled as containing GMO products if the amount is less than 1 per cent, or the GMO's DNA has been removed during processing, therefore it is no longer considered to be a GMO.
Green Party co-leader Metiria Turei told TVNZ's Q+A programme that at the heart of the matter was the right for people to decide whether or not to consume GM products.
She wondered if standards set by the Food Standards Australia New Zealand were being met and whether the food labelling was sufficient to give families the information they needed to decide whether to consume GMOs.
"People might want to avoid them for ethical reasons or cultural reasons or for health reasons. The question is, how much information are they given so that they can make that decision."
Ms Turei said all foods that are processed with GMO products should be identified as having a GMO in it.
There might be some science that indicated GMO with its DNA destroyed was not harmful to consumers, she said.
"But at the end of the day New Zealanders have the right to have confidence in the labelling of their food and they do have the right to know.
"If they don't have the information available, they can't make an informed choice."
The Ministry for Primary Industries had not performed any systemic monitoring of GMO labelling since 2003, Ms Turei said.
"They said it was not a high priority for food safety, but actually, for consumers who want to know whether there's GMOs in there food...there does need to be systemic checking and monitoring of the labelling so people can have confidence in food safety."
Food Safety Minister Nikki Kaye was unavailable to appear on the programme.