People who have received blood transfusions since January 1980 are to be banned from donating blood, the health secretary, John Reid, announced today.

Mr Reid said the move was being taken to avoid the "slight risk" of the transmission of variant Creutzfeldt-Jakob disease (vCJD). It comes after the government announced in December that a patient died of the disease - the human version of BSE - after receiving blood years earlier from a donor who contracted vCJD.

Mr Reid insisted this was still a "possibility, not a proven causal connection". But the government was determined to adopt a "precautionary approach" by banning blood donations by those who had received transfusions since January 1 1980.

He acknowledged this would lead to a cut in the supply of blood available to the NHS and urged better use by medical practitioners to avoid any shortage.

Transfusions should only occur where there was a "clear clinical need" and medical practitioners must increase their efforts to make "more appropriate use of blood", since more was currently used than was clinically necessary. Mr Reid appealed for people who can donate blood to continue to do so.

In a statement, Mr Reid said: "We are following a highly precautionary approach. Although people may have concerns about the implications of this announcement, I would emphasise again that this action is being taken because of an uncertain but slight risk.

"People should, indeed, continue to have a blood transfusion when it is really necessary. Any slight risk associated with receiving blood must be balanced against the significant risk of not receiving that blood when it is most needed."

Mr Reid said a further 15 patients who had received transfusions from donors who had gone on to develop vCJD had been identified and the survivors contacted and informed "about the circumstances of their case".

The blood donor ban would apply only to those who had received transfusions after January 1980 because "it is generally accepted that there would have been no exposure to BSE in the UK before that date".

It was estimated that there could be a loss of 52,000 donors but measures were being put in place to compensate for this.