GM crops can be more damaging to neighboring flora and fauna than ordinary strains of sugar beet, maize and oilseed rape, the Government's farm trials have shown.
The experiments have disproved the theory that GM plants would interact with other species in the same way as their conventional counterparts. In particular, the impact on insects, weeds and hedgerow plants has proved radically different, the trial results have revealed.
GM enthusiasts have argued that the crops will not affect the countryside. But sources close to the trials say that the findings, now being assessed by experts, prove that the "null hypothesis" about GM crops is wrong.
The three crops in the trials, GM maize, oilseed rape and sugar beet, have all behaved differently to the conventional varieties grown beside them. Some have destroyed more insects and weeds than conventional varieties, although one crop, believed to be maize, is thought to have had a more positive effect on killing unwanted common "weeds".
One senior source close to the trials said: "The null hypothesis is wrong, that's what's come out of the trials clearly. What is consistent is there are differences in the impact of GM crops and conventional crops."
Three varieties of GM crops have been tested in hundreds of farm-scale trials. The Government is to base its decision on whether to grow GM crops commercially in Britain on the results of these trials.
Whitehall experts believe ministers will give the green light to grow one variety of GM crop in Britain, possibly maize, to send a signal to the Americans that they are not anti-GM. But two other varieties are expected to be rejected because they may damage the environment.
The secret results, which will be sent to a government advisory committee on environmental contamination, are being checked by scientists.
Biotechnology firms have been given a "license to pollute" because of a loophole in the law that allows them to escape prosecution, critics say. The law on growing GM crops will allow such companies to escape fines or even prison if they do not "deliberately" release GM material into the environment. The get-out clause has incensed environmentalists, who say it proves controls are not tough enough to stop GM crops spreading into the wild across Britain.
The 1990 Environmental Protection Act means farmers who allow GM seed to be mixed with conventional crops, creating GM hybrids, would escape prosecution if they could prove the transfer was unintentional. They are unlikely to be prosecuted if they "exercised all precautions" to prevent GM genes escaping.
2003 Independent Digital (UK) Ltd