A damning attack by Michael Meacher, the Environment minister, on genetically modified foods was disowned by his own department yesterday.
Mr Meacher, the minister responsible for GM food, said biotechnology was "not necessary" to feed the world and raised fears that genetically modified crops could present a long-term health risk to consumers.
"The human race has existed on this planet for about a quarter of a million years," Mr Meacher said. "We have been feeding ourselves perfectly adequately since overcoming problems of hunger in our early existence. GM is not necessary."
Mr Meacher's gloomy warning contrasts starkly with Tony Blair's avowed enthusiasm for the potential "massive" benefits of the technology.
The Department for Environment, Food and Rural Affairs, headed by Margaret Beckett, described Mr Meacher's attack as "his views" and indicated there was "creative tension" within Government on the issue.
Ministers are due to announce later this year whether they will permit GM crops to be grown commercially after years of tests.
But in an interview in The Ecologist magazine, published today, Mr Meacher makes no secret of his hostility to the idea, leaving his position in Government untenable if large-scale cultivation gets the go-ahead.
"The real problem is whether 10, 20, 30 years down the track, serious and worrying things happen that none of us ever predicted," he said. "It's these sorts of totally unpredicted problems that make me cautious."
Mr Meacher also took a swipe at Lord Sainsbury, the Science minister, who is linked to biotechnology firms.
Pointing out that the Government does not have the money or manpower to conduct its own tests, Mr Meacher doubted whether food companies can be trusted to give objective advice.
"The question is, can we trust the companies and be sure that they are telling us all they know? When asked if the system [of testing] is adequate, it is difficult to give the answer, 'Yes'. The system is trusting and that is worrying."
The Government announced a national debate on GM technology last year to form the basis of a decision on whether to allow commercialisation.
Mr Blair has described biotechnology as the edge of a new scientific discovery, but acknowledged that some part of public opinion regards it as a threat.
"Now we are facing a frontier of this kind," he said. "The science of biotechnology will probably be, to the first half of the 21st century, what the computer was to the second half of the 20th century. Its implications are profound; its benefits, potential and massive."
Downing Street refused to endorse Mr Meacher's comments yesterday. A spokeswoman said: "That's a matter for [the Department for Environment, Food and Rural Affairs]."
Mr Meacher has repeatedly risked the wrath of ministerial colleagues with his outspoken comments. He has admitted that Britain was being pressed by the US to allow commercial planting.