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Urgent appeal for blood donors as stocks run low

20 December 2010 Last updated at 16:17 GMT

The NHS is appealing for people to donate blood because of low stocks caused by the bad weather.

The NHS Blood and Transplant Service said stocks of O negative have fallen below "preferred levels".

O negative is an a key blood type because it can be given safely to patients in other blood groups.

The BBC's medical correspondent Fergus Walsh, who has O negative blood visited a blood donation session in London.