'GM wheat trial belongs in a laboratory'
2 May 2012 Last updated at 17:38 BST
Scientists developing genetically modified wheat have appealed to campaigners not to ruin their experimental plots, in an open letter.
The trial at Rothamsted Research in Harpenden, Herts, uses wheat modified to deter aphids, an insect pest.
But the protest group Take the Flour Back has vowed to "decontaminate" the site unless the research is halted.
Speaking to the BBC one of the groups members, Lucy Harrap, said that she had concerns about the trial being carried out in the open air, rather than in a laboratory.