Scientists are assessing the damage after a GM wheat trial was vandalised at the Rothamsted Research centre in Hertfordshire.
The GM trial, conducted by scientists from Rothamsted Research in Hertfordshire, aims to see whether transgenic wheat can repel aphids in the field.
It is understood that part of the experimental crop has been vandalised and at least one person has been arrested.
Details of the attack started to emerge in a series of tweets by Rothamsted scientist Toby Bruce on Sunday (20 May).
“Just heard there’s been an attack on our field trial, don’t know if crops were vandalised,” he wrote. “Very sad.”
Dr Bruce is leading the transgenic wheat research project at Rothamsted.
A spokesman for Rothamsted said a statement was likely to be issued later.
The non-commercial trial is being sponsored by Biotechnology and Biological Sciences Research Council.
“There was one intruder who has spread wheat seed on to three of the plots, but no apparent damage,” Dr Bruce revealed. “He has been arrested.”
Dr Bruce later added: “Oh dear, there’s more: Damage to plot 7 where he has cut off the tops of quite a few of the plants and collected the material.”
It is not known at this stage who was responsible for the attack. But anti-GM activists have been planning a “mass action” against the GM trial.
The “Take the Flour Back!” website urges opponents to GM crops to meet one week later at Rothamsted, on Sunday (27 May).
It adds: “Or take your own action in your own way, at your own time. Together we can stop this trial.”
The website includes a map showing the location of the GM wheat trial.
Earlier, Rothamsted sicentists pleaded with anti-GM campaigners not to destroy the experimental plots.
An online petition to muster support for the scientists was signed by more than 5,000 people, including the actor and broadcaster Stephen Fry.
But the protest group Take The Flour Back refused to back down, vowing to “decontaminate” the site unless the research was halted.