The BBC's science correspondent, Pallob Ghosh, reports on the latest GM trials

The government's Scientific Steering Committee (SSC) announced the details of the new trials on Thursday. The seven trials conducted in 1999 provoked extreme controversy, with two being destroyed by protestors and one by the farmer himself.

The next stage of trials will run for three years and assess the impact of GM crops on insects and plants in the area. The scientists' findings will determine whether the crops can be grown commercially in Britain.

But the SSC's report was immediately criticised by Friends of the Earth, a prominent anti-GM group.

Campaigner Pete Riley said: "The farm-scale trials are a con trick on the public. The government is allowing a massive increase in GM crops when hardly anyone wants to grow them, no-one wants to sell them, and no-one is prepared to buy them. The government should think again before it's too late."

Professor Chris Pollock, who leads the SSC said: "The committee has scrutinised the results of this year's farm-scale trials. We are now satisfied that the methodology is scientifically robust, and that we have a firm base from which to proceed to full-scale trials next year."

Greenpeace criticised

The SSC report strongly criticises another pressure group, Greenpeace. It says: "We were particular disappointed about statements made by Greenpeace claiming that the science was flawed, only days after an open seminar in London at which we presented the science case. Greenpeace and Friends of the Earth were amongst a packed audience that day and neither found any defects in design or project methodology."

Environmental campaigners have also argued that the scientists are too closely linked to industry and that their results will be biased.

Campaigners say the scientists are too close to industry

But Ian Woiwod, an insect ecologist involved in the trials said: "I am an ecologist who has very little direct dealings with the industry. There is no way we are doing anything just specifically for the industry."

Scientists across the country will be testing three GM crops that are resistant to a strong weedkiller. This makes it much easy to kill the weeds around the crop.

But the worry is that the insects that depend on the weeds will starve and this will drive away the birds and insects that prey on them.

Concern over pollen

In particular, the scientists will be checking on the 200 species that are most sensitive to environmental changes. The SSC report says future research should focus on the species which are indicators of long term change, and of change higher up the food chain. These include snails, caterpillars, beetles, weeds and seeds. But earthworm populations will no longer be monitored.

Professor Brian Kerry, of Rothamsted Crop research Centre said: "It is too early to state exactly the importance of these kind of crops to agriculture, and particularly agriculture in the UK, but what we do need is solid scientific information on which to base rational decisions, and that's what these field trials are about."

Organic farmers concerned about the spread of GM pollen by bees

But organic farmers are concerned about the spread of pollen in the wind. They fear this will carry genes from GM fields to pollinate their crops and thereby remove the crop's organic status.

FoE's Peter Riley said: "These trials threaten the livelihoods of those who are trying to meet the massive demand for organic and non-GM food."

There has been no change in the rule which requires a 50 metre gap around GM crops, despite evidence that pollen carries much further.

The SSC report does say that the trials must now be done by splitting fields in half and planting GM and non-GM crops side-by-side. Up to now, trials have taken place in "paired" fields, which were judged to be similar but could have differences which would affect the trial results.