A scientist whose controversial study first ignited fears over genetically modified food warned today the decision to approve trials of blight-resistant potatoes in the UK meant preventing cross-contamination was "almost impossible".
Dr Arpad Pusztai caused an academic uproar when he claimed in 1998 that rats fed on GM potatoes suffered organ damage.
Today the Hungarian-born nutritionist said he was opposed to the approved GM trials in Derbyshire and Cambridgeshire, which he described as an "extremely stupid move".
"If these potatoes are going to be grown on a large scale then it is almost impossible to avoid genetic contamination," he said.
"Sooner or later the same gene will get into our common potato.
"There is no demand for genetic modification in this country and it could be the death nail for the potato because it is not going to be bought by the general public."
He added that he felt the Government had approved the trials in order to change the public's negative attitude about genetic modification.
"We are dealing with a very unstable genome which will almost certainly be producing some toxic effects and if they get into our human food chain it will cause a huge calamity," he said.
"I think the general public will have a great deal to say about this and I don't think the local farmers will be overjoyed."
Dr Pusztai, who eats only organic potatoes, said he felt the company planning to grow the potatoes saw Britain as a "soft touch" as the trials would not be allowed in many other EU countries.
"If people agree that they don't want this, then it can be stopped," he said.
"There are very good natural varieties of potatoes and I think doing this is just playing with fire."
Dr Pusztai said his research found GM food could weaken the immune system of rats, stunt their growth and damage their internal organs.
His study was discredited by the Royal Society and he later retired from his job at Aberdeen's Rowett Institute.