Trials of genetically modified crops should be conducted within a national high-security facility or in fields at secret locations across the country to prevent them from being attacked and destroyed by anti-GM activists, scientists said yesterday.

Researchers spoke out after protesters ripped up crops in one of only two GM trials to be approved in Britain this year, and ahead of a meeting with government ministers, which has been called to discuss ways of providing better protection for crop trials in future.

Scientists claim the repeated attacks on their trials are stifling vital research to evaluate whether GM crops can reduce the cost and environmental impact of farming, and whether GM variants will grow better in harsh environments where droughts have devastated harvests.

Since 2000 almost all of the 54 GM crop trials attempted in Britain have been attacked to some extent.

In a meeting planned for early September environment ministers will be asked to consider establishing a secure GM crop facility at the National Institute of Agricultural Botany (Niab) in Cambridge, where the last remaining GM crop trial - of a blight-resistant potato developed by the German company BASF - is being conducted. Security for that trial, which includes a perimeter fence and 24-hour security guards, has cost more than £100,000. An identical trial at the site last year was damaged by activists in a night raid. In other proposals scientists will be seeking permission to conduct small-scale GM crop trials at undisclosed locations, and possibly a secure register to hold full details of their trials, instead of making them public. Under an existing EU directive GM crop trials in Britain can only go ahead once a full description of the crop, along with a six-figure grid reference that effectively pinpoints the planned location of the trial, have been made public.

Last month a Leeds University trial of cyst-resistant GM potatoes was destroyed by anti-GM activists. Howard Atkinson, who led the research, said the trial, which involved only 400 plants, was too small to be considered a threat to the environment, and that paying for costly security "to protect against zealots" was hard for a university to justify.

Atkinson called on the government to adopt a strategy similar to that in Canada, where small experimental trials of a few acres and less can be conducted in secret, with full disclosure only required for larger commercial trials. "We demand the academic freedom to gain knowledge and a society that doesn't allow scientists to do that has got a problem," he said.

Wayne Powell, director of Niab, backed the calls for greater security of GM trials, adding that the exact locations of trials was originally required to inform local farmers and growers that GM crops were being planted close by. "We have to look at the way we're doing trials in a way that ensures they don't get vandalised," he said. "The consequence of not having field trials is you reject these crops before society has had a chance to consider the benefits."

While North America and other countries have adopted mass growing of GM soya, cotton and maize, there are no GM crops grown in Britain.

Clare Oxborrow, a food campaigner with Friends of the Earth, said: "The government must stand firm and resist this attempt to keep the public and farmers in the dark over GM crop trial locations."