An alliance of 27 organisations including the Real Bread Campaign, has asked the government, funding bodies and Rothamsted Research to explain the need for the GM-wheat trials being conducted by the institute.
The field trials are testing a type of wheat that has been genetically modified in an attempt to repel attacks from aphid pests.
The alliance, which also includes the Bakers, Food and Allied Workers Union, has asked Rothamsted Research and the government for more transparency about the aims of the GM-wheat trials and to explain public expenditure on such trials when other methods for controlling aphids exist.