Fragile public confidence in genetically modified food is weakened further today by two developments. A leading scientist and a rare butterfly are the latest witnesses in the trial of what has become known as Frankenstein food.

The scientist is Sir Robert May, the Government's Chief Scientific Adviser; and the endangered insect is the monarch butterfly.

Sir Robert has contradicted Prime Minister Tony Blair's policy on genetically modified crops by backing a call for a four-year moratorium on their commercial release. In a letter to a national newspaper, Sir Robert states that ministers should not allow GM crops to be released on the market before 2003 "at the earliest". Mr Blair and his ministers have consistently denied the need for such a ban, insisting that a voluntary agreement with bio-tech companies will suffice.

Sir Robert's comments conflict directly with Government policy and will be a severe embarrassment to Tony Blair.

Most people do not know enough about genetic modification to be able to make up their minds on whether or not it is safe to eat food produced using such engineered raw materials. And it is this very doubt which should alert the Government to such concerns - for if we can't be certain about its safety, why on earth should we be expected to eat a mouthful of GM food?

The debate on GM food does not appear to be going the Government's way, so we should be alarmed by reports that ministers have been involved in what is described as "a secret spin offensive" to push the benefits of bio-technology. According to a leaked letter, suggested tactics include getting an "independent" scientist to speak up in favour of GM food on Radio Four's Today programme, and the finding of "third parties to author articles in the media".

A matter as serious as the food we put in our mouths should not be subjected to such spin tactics. This is why the media has kept the issue on the agenda, ensuring that the public remain as fully informed as possible. Enter the butterfly.

Reports today suggest that a genetically modified maize could possibly kill off one of America's most beautiful butterflies. Pollen from the maize killed the larvae of the monarch butterfly in laboratory tests. This might seem to be a distant butterfly in a distant land, but as an American researcher said: "This is a warning bell."

The Government should be listening to all the warning bells ringing on this issue.

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