Voters in Oregon prepare to decide whether their genetically modified food should be labelled

The decision of some farmers to plant crops which have been genetically engineered in the laboratory has fiercely divided opinion for many years. Tomorrow in America, there are votes in two states - Oregon and Colorado - on whether foods with Genetically modified - or GM - content should be labelled in the shops. Biotech and supermarket giants have spent more than 25 million dollars to oppose the plan. The BBC's Marie Keyworth reports now on the latest controversy and asks how much longer the global GM debate will rumble on.