Eighteen protesters yesterday occupied an Oxfordshire farmhouse close to a large-scale trial of genetically modified oil seed rape is being grown.
The trial is at Model Farm near Watlington, and the protesters have renamed the neighbouring Clare Hill Farm as the Alternative Model Farm and begun transforming it into an organic garden for a national rally on nearby land to be held a week tomorrow.
They arrived at 3.30am but by last night the Earl of Macclesfield, whose family owns both farms, and the police had taken no action. The seized farmhouse is derelict but structurally sound and is being repaired by its occupants.
Lord Macclesfield said: "It is a disgrace these people should occupy private property.
"The place to make their protest is at the Commons, where they would be locked up for their pains.
"Unless we give proper trials to this crops, as Tony Blair intends, we will not be able to gather the scientific evidence to see whether they are safe or not."
The GM crop, which occupies a field the size of 25 football pitches on the opposite side of the road, is flowering. It has been modified by the agrochemical company AgrEvo to tolerate its total herbicide, Liberty; when the field is sprayed, every weed and insect is killed - all that survives is the crop.
The farm-scale trial is designed to assess the effect of this method of farming on the abundance of wildlife and is one of a number planned over four years. The government may refuse a certificate for commercial growing of certain genetically modified crops if it can be shown that this spraying method is detrimental to the countryside.
The protesters said in a statement: "Much wildlife, including song birds, is already under threat from industrial agriculture, and there is concern that GM crops will intensify this pressure and could lead to species extinction."
Among the protesters is Kathryn Tulip, a veteran of Genetix Snowball, the symbolic campaign of pulling up genetically engineered crops owned by another multi-national, Monsanto. She is one of six fighting an injunction by Monsanto on the grounds their action is justified in the public interest.
Mark Lynos, another protester, said the national rally was intended to continue pressure on the GM industry and draw attention to the potential damage to the countryside. "The sheer scale of this monoculture has got to be seen," he said.
"We are doing this to keep the issue in the public eye."