Farms growing both GM and traditional crops will find it extremely difficult to guarantee that non-GM varieties do not become so contaminated with genetically modified material that they will be impossible to sell as standard food, a European Commission report has claimed.

Under EU rules, traditional crops may not contain more than 1% GM content.

“Even with significant changes in farming practice, the cultivation of GM and non-GM crops will be unrealistic even on large farms,” states the report, which was produced by the EU Joint Research Centre’s Institute for Technological Studies.

It added that there would also be additional insurance and monitoring costs, adding 1% to 10% to production prices. For some crops, such as oil seed rape, this could be 41%, it added.