TOP SECRET trials of genetically modified (GM) crops are under way in North Yorkshire, it has been claimed.

GM maize is reportedly being grown on tennis court-sized plots under the authorisation of the Ministry of Agriculture, Fisheries and Food at an unnamed site in the county.

The secrecy surrounding the alleged trials - which are different from the farm-scale experiments being carried out in North Yorkshire - is said to be so tight that even the Environment Minister, Michael Meacher, who is in charge of GM crops, has been kept in the dark.

A Sunday newspaper reported that North Yorkshire is one of five English counties in which the maize, produced by Franco-German firm Aventis, is being grown.

It is said to have been genetically engineered to withstand spraying by a herbicide.

The Independent on Sunday reported that the GM crops are being cultivated side by side with non-GM plants so they can be compared for yield, disease and weather resistance and other characteristics.

They are reportedly being grown by the National Institute for Agricultural Botany under contract to the Ministry of Agriculture.

The secret tests are said to be entirely separate from farm-scale trials of GM crops, such as those underway at Ulleskelf, near Tadcaster, Nawton, near Helmsley, and Hutton Magna, near Richmond.

While the six-figure grid references for these trials were published openly, the Ministry of Agriculture is reported as saying it will, at most, only disclose the parishes where the tests are taking place, and then only on request.

The Tadcaster-area field of sugar beet was vandalised last month by protesters who hoped to prevent the crop from being harvested in the winter.

A spokeswoman for the Ministry of Agriculture, Fisheries and Food confirmed the trials were being carried out at a site in the county, but stressed the small scale of the tests.

She said: "This is from a national list of trials to test the quality of the seed, its ability to reproduce other seeds, to see if it's better than any other seed that's already on the market.

"They are done on small plots about 30 metres square. They are very, very small sites and they are often done within larger fields."

The spokeswoman added that the Government was committed to revealing the parish within which the trials were taking place if organic farmers nearby asked to know.

Friends of the Earth campaigner Josie Downs, who is part of the group Ryedale Against Genetically Modified Organisms, said: "Certainly concerned people like myself will be attempting to find out where these secret trials are being held.

"I would be interested to know how this came to light," she said, adding that she thought it was only right that farmers and bee keepers living near the site should be made aware of what is going on there.

"There are people who would be concerned about the growing of these secret plots and would want to tell the farmer or landowner concerned how they feel about it."