It would be "prudent" for New Zealand to opt out of the decision by an Australian-based ministerial council to accept the LY038 corn as fit for humans, the Sustainability Council of NZ said today.

"New Zealand has the right to stand aside from food safety decisions adopted in Australia," said the Sustainability Council's executive director, Simon Terry.

He wants an independent expert panel to oversee the design and interpretation of further testing of the corn as a human food.

And he said that with a range of maize cultivars being engineered for producing bio-ethanol, the Government should promote stricter standards for assessment, and make it a "transparent" process.

Food Safety Minister Annette King said in August she was seeking legal advice on whether it was appropriate to accept a trans-Tasman food standard for people on something intended as stockfeed.

"Animal feed is generally considered a primary production and processing (matter), rather than a food issue," she said at the time.

"I'm not comfortable with saying: just tick it off."

Monsanto asked for the corn - engineered to contain large doses of the amino acid lysine to add weight to pigs and poultry - to be approved for humans by Food Standards Australia New Zealand (FSANZ) because the biotech company expects it to turn up in corn-based foods through post-harvest contamination of food crops.

In 2000, a GE corn called StarLink, approved for use only as animal feed, was found in the human food chain, sparking a global recall of taco shells and corn-products foods from supermarket shelves.

Mrs King said the food treaty underpinning FSANZ did not cover New Zealand's primary production and processing standards, and New Zealand's own Food Act only covered food for human consumption. But New Zealand has previously approved a GE alfalfa feed for livestock as safe for humans.