The Welsh Blood Service is making an urgent appeal for donors particularly with type O & A negative blood to come forward and make a lifesaving donation.
It says the recent hot weather has affected the number of donors coming forward, seriously reducing stocks.
Patients undergoing surgery and receiving treatment for cancer and blood diseases, such as leukaemia, could be at risk of not getting transfusions they need.
The services says it cannot meet the needs of hospitals without the support of the people in Wales.
"At this difficult time we need their support more than ever", says Dr Geoff Poole at the Welsh Blood Service.
"Our blood stocks are at a seriously low level and we are making an urgent appeal for fit and healthy donors and those donors who have not donated for a while to come forward and help."
To increase their blood stocks the Welsh Blood Service is holding two special blood donation clinics at its headquarters in Talbot Green today Wednesday 17th and tomorrow.
To make an appointment call 0800 252266 or visit www.welshblood.org.uk
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