The Irish Blood Transfusion Service (IBTS) issued the directive after its donations fell below the minimum of 3,000 units required every week.
“Despite intensive efforts by the IBTS to offset the decline in donations, we have been left with no alternative but to notify the hospitals that we are unable to meet their demands for blood at this time,” said IBTS chief executive Andrew Kelly.
IBTS chairwoman Maura McGrath said: “The board of the IBTS regrets the impact of this decision on individual patients. We understand the inconvenience and upset it has caused. We value our donors who give so generously and encourage people to come forward to donate so we can meet patient needs.”
A spokesman for Tánaiste and Health Minister Mary Harney declined to comment, saying the matter was one for the blood bank. “It’s not an issue for us,” he said.
Fine Gael health spokesman Dr Liam Twomey said he was surprised the situation became so bad without a call for donors going out.
“It seems very drastic that this has happened without us being made aware there was a shortage coming along,” he said.
Although he conceded this was a difficult time for blood donations, Dr Twomey said there should have been more careful monitoring of blood stocks so an emergency appeal could have been made.
Labour health spokeswoman Liz McManus said she was shocked that such a shortage could be allowed to happen.
“This must have been growing as a problem for some time. It’s very disturbing, particularly after all the good work that the IBTS has been doing lately.”
Stephen McMahon, of the Irish Patients Association, said: “We are obviously very concerned that this situation has arisen and we would urge the public to donate blood urgently on behalf of patients all over the country.
An IBTS spokeswoman said: “This is a problem that has arisen over recent months despite intense effort by the organisation to increase the number of people visiting clinics.”
She said the service would keep the directive to halt pre-planned surgery under review. Hospitals will be able to carry out emergency surgery.
IBTS donor services manager Kieran Healy said the service was struggling to meet the blood donation targets due to a number of factors, including regulations introduced to prevent transmission of vCJD.
The number of donations has also been affected by the recent good weather and bank holiday weekends.
There are large shortages of all blood types. However, the IBTS said it wanted regular donors rather than a one-off rush. “We need a constant and regular supply. If we get an overwhelming response, the capacity we have to absorb it is limited in a short space of time,” said the spokeswoman.