A survey of over 2,000 adults by Unison showed that three out of four were opposed to any move to have private companies running parts of the NHS blood and transplant service.

General secretary Dave Prentis said: “The public have said a very resounding no to blood money. The blood and transplant service is an inspirational service with millions of people willing to give their blood freely with no money exchanging hands.

“Letting private companies move in breaks that link and taints the whole service with the profit motive. There are also very real dangers to the safety of the blood supply if the smooth path from donors to patients is broken.”

A Department of Health spokesperson said: “The review under way is exploring how further savings can be made and this includes continuing to outsource some activities. NHS blood and transplant will remain in the public sector: there are no plans to sell off any part of the blood service.

“We are not considering any functions that could risk destabilising the current national donor system. We have a wonderful system of altruistic donation of blood, tissues and organs in this country. We owe a huge debt of gratitude to all those who donate freely for the benefit of others.”