But unlike GM rapeseed, which is banned from being grown in France, several strains of GM maize have been approved for production in the European Union - including at least one variety whose genetic signature was detected in seeds imported to France from the United States. U.S. Seed company Golden Harvest said last week that it had detected GM material in supposedly non-GM maize seed it imported into France, but levels were so small as to pose no problem.

The government confirmed on Friday that it had detected the presence of GM material in the seed, which it said had been sold in 23 districts in southwest France. It pegged the area in which the seed was sown at 3,000 hectares.

It also said the seed in question contained some GM material approved to be grown in the EU, some GM material from a strain not yet authorised for production in the EU and some GM material from a "third, unidentified origin".

The fact that some of the GM seed detected among the Golden Harvest lots can be grown legally in the EU is one reason why calls for the destruction of the maize have been more muted than they were during last month's rapeseed debacle.

Christophe Labarde, a spokesman for French maize growers'group AGPM, also said that while GM rapeseed could spread its pollen to other plants, GM maize does not run such a risk.This, he said, was part of the reason AGPM has not called for the maize in question to be destroyed.

"The only reason justifying the destruction of this maize would be if it posed a danger to health and to the environment. On the basis of what we know, there is no danger," he told Reuters on Monday.

Vocal GM opposition
A source close to Jospin told Reuters last week that the government has not ruled out destroying fields planted with the seed, but that it was waiting for results from further tests before making a decision.Serving to complicate the government's decision, however, is the vocal anti-GM campaign being waged in France by farming and environmental activists.

This was highlighted on Monday after unidentified assailants broke into a government-controlled laboratory and destroyed GM organisms being studied there. The attackers left behind leaflets at the facility claiming the action on behalf of the "night researchers".

The incident followed similar raids over the past year on fields where GM crops were being grown experimentally.There is also pressure to destroy the maize from within Jospin's leftist coalition government, which includes France's Greens Party. The Greens, who are represented in the government by Environment Minister Dominique Voynet, last week demanded that the maize be torn up immediately and farmers be compensated for their resulting losses.