Briefings prepared for ministers, and seen by The Independent, warn that the imports pose a risk to health.
In a memo to John Gummer, the Secretary of State for the Environment, Dr William Parish, of the DoE's Chemicals and Biotechnology Division, warned: "[The maize] will be imported shortly despite the fact that it is not authorised in an unprocessed form, and that the UK objected to proposals to authorise it." He added: "Given that the UK objected to the unrestricted marketing of genetically modified (GM) maize, there is bound to be concern that the imported maize gluten feed represents a risk to human health and safety to the environment."
The new maize - known as Genetech Corn - is already being cultivated in the US and government sources said little could be done to keep it out.
The DoE memo warns: "The UK has no control over the mixing of GM and non-GM maize in the US.
"In practice, it is not possible to identify nor separate the GM maize once it arrives in the UK as a bulk commodity. Therefore, no one will know whether any particular shipment contains GM maize."
The Ministry of Agriculture Fisheries and Food (Maff) has objected to the GM corn on the grounds that it could compromise treatment of diseases in animals and humans.
The modified corn has been manipulated to be tolerant to herbicide and to poison insects which eat it, but it also contains a gene which is resistant to ampicillin antibiotics.
There is concern at Maff that if the GM maize was used in animal feeds it could lead to drug-resistant bacteria forming in the digestive system of livestock, compromising disease treatment in animals and humans.
Next week, Mr Gummer will attend a meeting of the EC Environment Council at which permission for marketing the GM maize will be discussed. The council will consider research undertaken by the EC Scientific Committee on Food, the Scientific Committee on Animal Nutrition and the Scientific Committee for Pesticides. Britain must abide by the council's decision.
Ciba-Geigy, the company which developed the genetically modified maize seeds, is confident it will get approval to market the product. Daniel Blancpain, world-wide Head of Ciba Seeds, said: "We agree with the Commission that no efforts should be spared in order to ensure that our product can be widely accepted and be met with confidence by the public."
When the GM maize is processed for human consumption, by boiling or cooking, it is believed to be safe.
However, Maff asked the Laboratory of the Government Chemist to see if any of the DNA in the modified product would remain after processing.
The briefing states: "It appears that fragments can survive and Maff are now seeking the views of independent experts . . . about whether this changes their view on the risk of processed maize."
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