Valuable overseas customers could be lost if New Zealand begins growing genetically modified food crops, according to the Greens.

Green Party GE spokesperson, Jeanette Fitzsimons, told the NZ Institute of Agricultural and Horticultural Science the European and Japanese markets have strong consumer resistance to GM foods.

"While their governments may allow tolerances of minor contamination at the border, the consumer and therefore those who supply them don’t.

"Even a barely measurable GM contaminant in a corn pizza topping led to its rejection in Japan. If such rejections become more frequent it will damage our brand overall," she added.

"If there is money to be made from GM, it is not made by the growers, but by those who hold the IP. This will not, on the whole, be New Zealanders. The global seed market is controlled by some five transnational firms.

Fitzsimons concluded, "…the best way I can describe Genetic Engineering of crops and animals is as a clever and expensive technology looking desperately for a use – a smart solution looking for a problem."