GE Free New Zealand says the amount of genetically engineered stock feed being used in the dairy industry needs to be investigated.
The industry has acknowledged that some genetically modified supplementary feeds including cotton seed, soybean meal and canola are imported into New Zealand.
GE Free NZ spokesman Jon Carapiet says it is worrying that no-one is sure how much is imported.
He thinks hundreds of thousands of tonnes of genetically modified feed is given to New Zealand herds annually, and an investigation is needed, because New Zealand's global reputation is at stake.
Mr Carapiet says it's time the dairy industry acknowledged that far more genetically modified feed is being used than previously thought.
Fonterra and Dairy NZ have indicated they will be responding to these claims.
