Seeds planted over the Easter weekend at Lushill Farm in Hannington, near Swindon, Wiltshire, will be allowed to grow, despite people in the area not being informed by a notice in their local paper that the trial would be made.
Under the rules of the Department of the Environment, Transport and the Regions (DETR), any company intending to grow GM organisms outdoors must place a notice in a paper serving the local area.
On the Today programme yesterday Michael Meacher, the Environment minister, insisted that the Gloucestershire Echo - where an advert about the planned planting appeared on March 9 - did cover the area. But the Echo insisted its 26,000 circulation stopped at Cirencester, about 15 miles northwest of Hannington.
Although that means AgrEvo, which provided the seeds, is clearly in breach of the Government's rules, and Mr Meacher was at best misinformed, a spokesman insisted the trial will go ahead in spite of any objections. "DETR wants these trials to go ahead," he said. "They are the first on this scale which have been done, and it is very important that we get this information."
Friends of the Earth has written to Mr Meacher, calling on him to order the 25-acre crop of spring variety oilseed rape to be ploughed up. Pete Riley, Friends of the Earth food campaigner, said: "The Government must take decisive action and stop these farm-scale trials until the correct procedures have been followed."
Four such trials are expected, to assess the environmental impact of growing GM herbicide-resistant rape and maize. Another trial will begin near Shirburn, Oxfordshire, later this month.
Desmond D'Souza, biotechnology director at AgrEvo, said his company acted in good faith when it advertised in the Echo, and the company was re- advertising in the Swindon Evening Advertiser in the interests of "openness and transparency". The first adverts appeared yesterday.
"We do not accept that we have breached the laws," he added. "We advertised in good faith in what we believed to be the right paper. The laws state that we must advertise in a local paper within 10 days of consent being applied for from the Department of Environment, Transport and the Regions to go ahead. We did this. We do not accept that we advertised in the wrong publication.
"We will not be harvesting until some time after July. The public still have every opportunity to register objections."
The DETR wants to institute field-scale trials of GM crops as a means of slowing their commercial introduction, thus appeasing pressure groups, while providing a path to their wider use, thus satisfying the companies.
The Cooperative Wholesale Society, the UK's largest farming organisation, has refused to take part in trials.
Thousands of people are expected to march in London today to call on the Government to ban GM food. The protest, organised by GMO Campaign, starts in Hyde Park at 1.30pm and ends at Trafalgar Square.