The Government's decision to allow commercial growing of genetically modified crops in the UK flies in the face of public opinion and many of the conclusions of its own advisors.

Next week, Margaret Beckett, the Secretary of State for the Environment, is expected to announce that on the advice of the Advisory Committee on Releases to the Environment (Acre), the Government agrees to the commercial growing of GM maize in the UK.

The announcement comes just three weeks after the Leader of the House, Peter Hain, told MPs: "I am sure that there will be no question of proceeding with any decision until the debate has occurred." But the debate sought by MPs of all parties has never taken place.

Moreover, leaked minutes from the Cabinet Sub-Committee on Biotechnology underline the determination of the Government to thwart the democratic process and attempt to present this highly-political decision as entirely evidence based. Cynically, the committee also proposed using examples from the developing world as a means of gaining public support.

Over the past year, a series of official reports into GM crops has been published. We have had GM Nation? (the report of the steering board of the national public debate on GM); the Prime Minister's Strategy Unit report into the economic impact; two reports of the GM Science Review panel; the results of farm scale trials and the official advice from Acre.

With each report, MPs including myself, have demanded a parliamentary debate because of the issues raised. Our requests have fallen on deaf ears.

The Government knows that the case for authorising herbicide-tolerant GM maize is weak, but it is a sufficient fig-leaf to give the biotech companies what they want. The maize is designed to be treated with glufosinate, which is sold by Bayer, the same company that produces the seed. Farm-scale evaluations tested whether there was any difference between the effects on farmland wildlife of GM and non-GM maize. GM maize proved better for wildlife than its non-GM counterpart. But the results were soon called into question when it transpired that the non-GM maize had been treated with atrazine, a more powerful herbicide than glufosinate, and recently banned by the EU.

The advice that GM maize would be better for biodiversity than non-GM maize was hedged with conditions and called for further work in relation to non-GM maize and atrazine. Even less support for the Government's position can be found in the public debate or the other specialist reports. GM Nation? found "little support for early commercialisation" and "widespread mistrust of government and multinational companies". Most significantly, it found the more the public engaged in GM issues, the harder its attitude and the more intense its concerns became.

Uncertainties were also underlined in the science review : "The main special feature of GM plant breeding is that it allows a wider choice of genes for modifying crops in novel ways. No other plant breeding technique permits the incorporation of genetic material from such diverse biological sources. Inevitably, this raises the possibility that some new consequences of GM plant breeding may be unexpected."

The report of the Prime Minister's strategy unit meanwhile forecast little economic benefit for UK agriculture. It concluded that in the short term "negative consumer attitudes" would limit the demand for GM foods, and therefore the economic value of the current generation of GM crops.

With the public hostile, the economics unproven and the science uncertain, why does the Government persist in foisting GM on the UK? The only answer that appeared to emerge in the Cabinet sub-committee was the symbolic importance of the decision for the Government's science policy and the UK science base. Yet science policy is led by Lord Sainsbury, who has had financial interests in GM, and the science base is in no way dependent on the minute GM crops sector.

The case that GM crops are necessary to feed the world is even less well made. Golden rice, genetically engineered to contain beta-carotene, the precursor of vitamin A, is the quoted example. Yet the President of the Rockefeller Institute, which helped to finance the research, has accused the food industry of using golden rice for its own ends as part of a $50m campaign to promote GM foods. "All the hype is premature and dangerous," he said. "Until the product is fully developed and tested, no one can be sure how well it will work and whether there may be unwanted side-effects."

Aid agencies concur. "Claims that genetically modified organisms are necessary for the food security of poor people in developing countries should not be used to promote public acceptance of GM by the UK public," the directors of Action Aid, Cafod, Christian Aid, Oxfam and Save the Children wrote to the Government in 2002.

GM crops do not have to be grown in the UK. Other countries will fight hard to keep them out. The Bush administration has challenged the EU moratorium on GM at the World Trade Organisation - but why shouldn't we fight that? Parliament has signally failed to represent the views of the public on GM food and crops. Once again, public trust in elected representatives is likely to be undermined.

The writer is the Labour MP for Lewisham Deptford