A protest group is demanding the immediate closure of all genetically engineered field trials after identifying a safety breach at a trial site in Canterbury.
The Soil and Health Association says a genetically modified brassica plant at a Plant and Food Research site in Lincoln has flowered, putting nearby non-GE crops at risk of cross-pollination.
The association says the flowering GE plant was found during an unannounced visit before Christmas.
It says this shows that the 10-year field trial is "sloppy and environmentally dangerous after just one year of operation".
Plant and Food Research spokesperson Bruce Campbell acknowledges a safety breach has occurred, but says it is unlikely to pose any significant threat to nearby crops.
Mr Campbell says the government-funded institute is taking the mistake very seriously but does not believe it will harm nearby crops.
However, Elvira Dommisse, a genetic engineering specialist, says careless maintenence of the field trial could pose a serious threat to the export market.
Dr Dommisse, who worked for Crop and Food Research while studying the genetic modification of onions, says the attitude towards the control of field trials is too relaxed.
She says Crop and Food Research is not taking into account the danger of genetically modified material mixing with New Zealand agriculture through the process of cross-pollination.
She says New Zealand exporters promise a GE-free products and it would take only one mistake during a test to contaminate nearby crops and threaten the entire market.
She also says there is not enough research into the harmful effects of a genetically engineered toxin used during the field trial. Many growers use the toxin in spray form several times a season to keep insects away.
But she says the plants have been modified so the toxin is constantly present and cannot be broken down in the same way a spray would be.
Dr Dommisse says other field trials have shown animals died after eating plants carrying excessive amounts of the bacteria.