"The most likely economic impact from the careful and considered release of genetically modified organisms would be a small increase in gross domestic product over 10 years, compared to a small decrease from forgoing GMO releases," Hobbs said.

The economic study of the costs and benefits of releasing genetically engineered organisms was drawn up by private research house Business and Economic Research Ltd as one of the last studies asked for by the Government before the moratorium on commercial releases of GMOs is lifted in October.

The study canvassed three specific examples of releases in pastoral agriculture, pest control, and human therapeutics, and tested them on two economic models - an agricultural trade model and an economy-wide model.

It investigated the costs and benefits of releasing GMOs and of not releasing them.

From the agricultural model, the release of a genetically modified crop or animal that boosted annual productivity 2.5 percent for 10 years with no change in market demand led to a 5.1 percent rise in returns for farmers.

But a scenario where such a release drove down the prices available to New Zealand dairy, meat and fruit exports, cut farmer earnings by 43 percent.

In the economy-wide model, the impacts of productivity changes were relatively greater and the impact on export returns more muted.

Assuming the GMO release did not raise productivity, the economy-wide model found that gross domestic product in 10 years would be 2.4 percent lower than it otherwise would have been, with dairy and meat export returns 8.2 percent lower.

But conversely a GMO release which generated an assumed annual 2.5 percent higher productivity in pastoral agriculture would leave GDP 2.5 percent higher in 10 years, with dairy and meat export returns 8.9 percent higher, the paper said.

Nearly half of New Zealand's NZ$31 billion annual export earnings come from meat, wool, dairy, and fruit products.