The campaign to legalise the commercial growing of genetically-modified oilseed rape in the European Union received a setback on Wednesday when Belgian scientists advised it would be harmful to the environment.
The Belgian biosafety advisory committee said a herbicide-tolerant oilseed rape variety made by Bayer Cropscience would damage wildlife and mix with non-GM wild varieties through a process called vertical gene-flow.
Although measures could be taken to reduce the crop's impact on the environment, these would be "impracticable, hardly workable and hard to control in current agricultural circumstances - hence vertical gene flow and negative consequences on biodiversity may not be controlled," the committee said.
Its recommendations could be far-reaching. Belgium is acting for all member states in considering the application from Bayer. The scientific advice will now be considered by Belgian ministers and any rejection of the application would apply across the EU. However, Bayer could appeal to the Belgian courts for the decision to be overturned.
Bayer said the scientists' advice did not prevent its product gaining eventual approval but this would require the company being able to show that measures to reduce its impact on the environment could work effectively.
The committee relied upon conclusions reached by British scientists, who carried out the largest environmental experiment on the effects of herbicide-tolerant rape, maize and sugarbeet on the environment. It concluded that growing GM rape and sugar beet was more damaging than cultivating non-GM crops, but GM maize was less damaging.
The scientific advice applies only to oilseed rape sown in the spring. The impact of winter-sown varieties is still being considered.
However, in a separate move, the European Commission on Wednesday backed a proposal to allow imports of a genetically modified maize type, the first step towards lifting the EU's five-year unofficial ban on new GM crops and products.
EU governments now have three months to consider the proposal to allow imports of the maize, known as Bt-11 and marketed by the Swiss agrochemicals group Syngenta. If they cannot agree by then, the Commission may rubberstamp its own proposal.
The US, backed by Canada and Argentina, has challenged the EU's ban at the World Trade Organisation, saying it is acting illegally. Farmers in the US say the ban costs them millions of dollars a year in lost sales.