Government health advisors meet tomorrow to discuss the findings.

Until now, it has been assumed that BSE-infected meat was responsible for only the variant CJD - a disease identified in 1996 and affecting mainly young people.

But experiments with mice by Prof John Collinge and colleagues at University College London suggest a link between BSE and what has until now always been known as "sporadic" or classical CJD.

It has always been believed this condition was caused by a normal prion protein in the brain spontaneously changing into the abnormal dangerous form.

But Prof Collinge's research suggests that many of the classical CJD deaths may indeed be diet-related.

During the experiments mice were injected with BSE - Bovine Spongiform Encephalopathy - and saw them develop both the variant and sporadic strains.

Prof Collinge said the findings may change the way in which victims of CJD are counselled.

Prof Collinge said the findings could mean huge changes in the counselling of sporadic CJD patients and their families.

"When you counsel those who have the classical sporadic disease, you tell them this is not related to what you read in the newspapers, it arises spontaneously out of the blue.

"I guess we can no longer say that."

The Department of Health has confirmed its specialist advisory body on CJD - the Spongiform Encephalopathy Advisory Committee - will be discussing the implications of the findings tomorrow.

Last night Margaret Guy, whose mother Doreen, 61, of Seaham, County Durham, died of "sporadic" CJD in 1993, said the new research gave hope to those who had not yet been given any satisfactory answers.

"There are hundreds of us who just feel our cases have been swept under the carpet and ignored," said Margaret, who now lives in Chiswick, London.

"My mum died of CJD the same as anyone else - it never made any sense to say that cases before 1996 were one form of the disease and after that date were a new form.

"It always seemed so random.

"What we need now is a full investigation so this vital report is not ignored."

Deaths from sporadic CJD reported in Britain in the 1990s peaked at around 89 a year in 1998 and the number has stayed around the 80 mark ever since - far more than the 28 variant CJD cases in 2000, the worst year so far for variant CJD.

The number of people in the North-East officially confirmed to have died of vCJD is 13.

The number thought to have died of classical CJD is believed to number at least 200.

A spokesman for the Department of Health said: "These are interesting and potentially important findings, which we will need to consider in detail."

The £55m in compensation given by the Department of Health is not available for sporadic CJD victims or relatives, and there is no way yet scientists can distinguish between cases that arose from spontaneous changing in the form of the prion protein linked to both diseases, and those that might be diet-related.

Newcastle scientist Dr Harash Narang, who has spent many years researching CJD, said: "What Professor Collinge's research shows is that many of those who have been classified as dying from sporadic CJD in the past may in fact have died from BSE."