The Health Minister Mary Harney has said that up to €1bn will have to be slashed from the HSE budget next year.
Already pared back by more than €1bn this year, Ms Harney said further cuts will have to be made in the months ahead.
She said discussions are underway between Department of Health officials and the executives from the HSE.
She admits the cuts that have to be made won't be easy.
Ms Harney said: "It will be somewhere between €600m and €1bn. There is no easy way to take that kind of money out.
"Given that payment rates can't be cut under the Croke Park Agreement - and 70% of our budget is pay - so you are talking about taking that amount of money out of the remaining 30% and that is going to be really challenging."
SIPTU has reacted angrily to the comments, saying Ms Harney's axe is "too blunt".
It is warning that cuts on this scale will affect the viability of many hospitals.
Meanwhile, head of the Irish Congress of Trade Unions David Begg is calling on the Government to implement a longer period of adjustment to get the economy back on track.
Mr Begg said December's budget cuts should be in the region of €2bn to €3bn.