The British Environment Secretary, Mrs Margaret Beckett, has given a qualified go-ahead to the commercial cultivation of genetically modified herbicide-tolerant maize.
But she told MPs in a Commons statement that Britain should oppose the commerical growing of GM beet and oilseed rape.
Her long-awaited announcement, in the face of widespread opposition from environmental and consumer groups, follows five years of consultations and farm-scale trials into the impact of GM crops on the environment.
Mrs Beckett said agreement "in principle" to the commercial growing of GM herbicide-tolerant maize would be "only subject to further important conditions".
She told MPs: "Restrictions should be imposed on the existing EU marketing consent which expires in October 2006 so that this maize can only be grown and managed as in the trials or under such conditions as will not result in adverse effects on the environment."