A British patient has died from CJD, the human form of BSE, after being given a blood transfusion infected with the disease, the health secretary announced in an emergency Commons statement today.

The man, who has not been named, showed no symptoms of CJD when he received the transfusion for a life-threatening illness in 1996, John Reid told MPs, but had this year died of the disease.

Mr Reid stressed there was no proven causal link between the two events, but if the dead man died as a result of the blood transfusion, it would be a world first.

A further 15 patients have received infected CJD blood, and were being offered counselling, he added.

The health secretary told the Commons: "It is because this is the first report from anywhere in the world of the possible transmission of CJD from person to person via blood that I thought it right to come to the despatch box to inform the House on a precautionary basis."

"The link between the donor and the recipient was first reported to officials in my department on December 9 2003, at which time the diagnosis of CJD in the recipient was still being confirmed.

"I was first alerted to the developments on Friday December 12 and was briefed by the chief medical officer on Monday and Tuesday this week.

"I have given the minimum clinical details of the recipient because the family has indicated they wish to have their privacy protected."

Dr Reid said: "It is therefore possible that the disease was transmitted from donor to recipient by blood transfusion in circumstances where the blood of the donor was infectious, three years before the donor developed CJD, and where the recipient developed CJD after a six-and-a-half-year incubation period.

"This is a possibility, not a proven causal connection.

"However, it is also possible that both individuals separately acquired CJD by eating BSE-infected meat or meat products.

"This is a single incident, so it is impossible to be sure which was the route of the infection. However, the possibility of this being transfusion-related cannot be discounted. That is the conclusion of the chief medical officer and experts.

The health secretary said it was important to remember blood transfusions could be a vital life saving treatment and Britain had a reputation for a "very safe" blood service. Furthermore there had been just 143 UK cases of CJD.

There is still no blood test for CJD or BSE, Mr Reid told MPs, but the government has put a range of precautionary measures in place.