The Irish Blood Transfusion Service (IBTS) warned yesterday that it might not be able to meet hospital demand for blood because of dwindling supplies.
Poor attendance at blood clinics because of the freezing weather conditions has been blamed for the fall in supplies.
The bank said it would need up to 800 donors over the weekend to get supplies to where they needed to be.
IBTS operations director Paddy Bowler said the sustained shortfall in collection had reduced supply to five days of O-positive and just three days of O-negative.
In a normal pre-Christmas situation the blood bank would have between five and nine days of blood stocks, depending on the blood group.
“The IBTS has only been able to meet 75-80% of our collection targets over the past three weeks and this has put significant strain on the blood supply,” he said.
He said the bad weather had affected the ability of donors to get to clinics and six extra clinics were planned tomorrow in a bid to replenish supplies.
On Wednesday the IBTS asked hospitals to be careful in their use of O-negative and A-negative blood in particular.
“If we cannot increase attendances at clinics over the next few days, we are predicting shortages across all blood groups by the end of next week,” he said.
Mr Bowler warned that if supplies continued to decline hospitals would not be able to continue with scheduled elective surgery.
He said the IBTS would consider calling in the army to help with collection of blood supplies, if the situation deteriorated further.
“Out of 70 clinics, we lost three. That would not normally affect us that badly. Our biggest problem is actually the number of donors coming through the door,” he said.