"Strict identity preservation could easily double the price of soybeans," Jerry Slocum, president of the North Mississippi Grain Company, told the Agra Europe conference.

The European Commission has devised the traceability system as part of its new so-called farm-to-fork approach to food safety and to appease member states' concerns over GM food, which has led to no new varieties being approved in the EU for three years.

The proposal, if adopted by EU governments and the European Parliament, would require imported GM soybeans and grain, as well as processed foods, to carry details of their origin and path through the production chain.

"I can't imagine an exporter from the United States would take on the liability of shipping a cargo without knowing what was in it," Slocum said. "The way we read it (the proposal), it leads all the way back to my farm in northern Mississippi."

Given the way grain was harvested and transported to ports for export, only complete segregation from start to finish could guarantee there was no mix between GM and traditional varieties.

Slocum said a 50,000 tonne shipment of soybeans, for example, could contain seven million beans from perhaps thousands of farms across the United States.

However, the tough rules are probably the only way EU governments will end their de facto moratorium on new approvals, even though some want to go even further and introduce rules to hold GM producers liable for any damage to the environment.

European food safety Commissioner David Byrne and environment Commissioner Margot Wallstrom have recommended restarting GM approvals based on the current traceability and labelling proposals, even though they could be up to three years away from being officially adopted as national laws.

They believe the present impasse could be illegal and leaves the EU open to challenge at the World Trade Organisation.