The Irish Nurses Organisation has said that a €1bn cutback in health services would be catastrophic.
The union also said it would equate to the complete closure of four of the major Dublin hospitals or the loss of up to 10,000 jobs.
INO deputy general secretary Dave Hughes said that the Government must recognise that the health service budget could not have foreseen the increase in medical card spending and the loss in health levy contributions.
He added that the Health Service Executive must receive extra funding in the same way that the Department of Social, Family and Community Affairs is being provided with additional money to deal with the increase in unemployment.
Mr Hughes said the public will ask how banks can be granted in excess of €7bn this year while already overstretched health services are to be cut by €1bn.
Children's Hospital faces financial constraints
Our Lady's Children's Hospital in Dublin has told RTÉ News that its budget allocation for the year has been cut by close to €6m and it is facing 'unprecedented financial constraints.'
The hospital says staff are being asked for their voluntary expression of interest in taking unpaid leave during the summer, during which time Crumlin may reduce planned operations.
The hospital's allocation of €137m from the HSE represents a 4% reduction on last year's budget.
Crumlin says it is preparing a breakeven plan for the year, to protect in as far as possible, services for its sickest children.
Before any options are implemented, it says the effect on waiting times for patients, efficiency and cost savings will have to be fully examined.
