Sir John Krebs, chairman of the Food Standards Agency (FSA) has been heavily criticised and accused of manipulating the Government's public debate on GM foods.

Nine organisations including the Soil Association and Unison, the public sector trade union, have written to the food safety chief accusing him of bias towards GM crops and foods, and of misrepresenting the views of the public.

In its letter Unison said: 'There is a strong consensus among consumer and environment organisations that the published views and statements of the FSA and its chair are indistinguishable from those of the pro-GM lobby and do not represent public health and consumer interests.' Meanwhile, the UK's leading science academy, the Royal Society is warning that the impact of genetically modified crops must be closely monitored in the long-term if commercial planting goes ahead in Britain. In it submission to a GM crop inquiry it said: 'It is essential that regulators monitor the environmental impact to pick up any potentially beneficial or harmful effects over a long period.'