Preliminary results leaked from trials of genetically modified crops show that some are damaging the environment while others appear to be beneficial.

The results indicate that modified maize has reduced the use of herbicides, and stimulated the growth of grasses, weeds and seeds that prevent soil erosion and provide food for wildlife, reports the Sunday Times. However, modified oilseed rape and beet have done the opposite and are damaging the environment.

The results are based on date from the first two years of crop trials set to last another year. This weekend, the environmental department said Britain could see the first full-scale commercial planting of modified crops within 18 months, soon after the trial results become available.

The results will further fuel an increasingly heated debate over future application of genetically modified crops in the UK government. Science minister Lord Sainsbury, a keen advocate of GM crops is likely to come to verbal blows with environment minister Michael Meacher, who has been arguing for more concern to be shown for public uneasiness about genetically modified crops. However, it emerged this weekend that Meacher's boss, environment secretary Margaret Beckett, is concerned that Britain should benefit from GM technology.