A drop in people giving blood over the Jubilee weekend led to national blood stocks falling by 7 per cent, NHS Blood and Transplant has warned.

National Blood Week kicks off today and the NHSBT is urging the public to become donors and join the 4 per cent of the population who currently give blood.

Past experience shows that even regular donors miss appointments during national events and celebrations as people become distracted and routines are disrupted. Blood stocks fell by 20 per cent during the 2006 World Cup.

This year NHSBT needs to build a 30 per cent increase in blood stock levels ahead of the Olympics as the number of people donating during the London 2012 Games is likely to plummet.

During the National Blood Week recruitment drive, additional appointments have been created and selected blood donor sessions have extended opening hours to give donors more flexibility to schedule a visit.

Regional recruitment events will also be driving awareness and enabling people to sign up.

NHSBT spokesman Jon Latham said: “We know from experience that major public events have a big impact on blood stocks so we prepared ahead for the Jubilee to build stocks in advance but we now need a huge effort from the public ahead of a summer of sport.”