The NHS has said that it needs to increase stocks of donated blood ahead of a summer of major national events.
It has called for donors to come forward to help cope with huge public events such as the Olympics in London, extra public holidays and Jubilee events across the UK.
NHS Blood and Transplant (NHSBT) has launched an appeal for donors to help boost stocks to 30 per cent above usual levels by the start of the Olympic Games in July.
The increase is needed because past experience shows that even regular donors miss appointments during national events and celebrations as routines are disrupted.
This, combined with the high numbers of international visitors with a different native blood mix, may also put high demand on specific blood groups.
Jon Latham, spokesperson for NHS Blood and Transplant, said: "This year we have a unique situation and need the public's help to counterbalance the inevitable dip in donations as people celebrate a memorable summer for the country. We need to adjust the mix of stocks so we are well prepared as a responsible host for these exciting events."