SIPTU has said that it may seek industrial action over Health Service Executive proposals for longer working hours and lower overtime rates for health sector workers.
The HSE is proposing that all staff to work an extra two hours a week in a bid to address its deficit of €280m.
Another proposal is that overtime will only be paid at a flat rate, rather than at time and a half or double time.
SIPTU Health Divison Organiser Paul Bell has described the proposals as a "crusade" led by Health Minister James Reilly.
Paul Bell has said that the plans are precluded under the protections of the Croke Park Agreemeent.
He said SIPTU would consider holding a protective ballot for industrial action when they receive a formal copy of the proposals.
The HSE Director of Human Resources Barry O'Brien said all the changes were needed to address its massive deficit which could top €.5bn by Christmas without radical action.
Elsewhere, talks on reforms and cost savings for hospital consultants have broken down.
The HSE will seek the assistance of the Labour Relations Commission to secure a speedy agreement in line with the time frame set out in the Croke Park Agreement.
The HSE said agreement on consultants reforms was an essential component in their overall health reform.
The Irish Hospital Consultants Association Secretary General Martin Varley said they were dismayed at 'management premature actions' as the consultants had offered to continue discussions throughout next week.
The HSE had tabled weekend rostering for hospital consultants.
It is also seeking a lower paid entry grade for consultants and the elimination of massive back logs of overtime known as historic leave.
Mr O'Brien said when he arrived at the talks that both the changes sought for general grades and hospital consultants were permitted under the Croke Park Agreement.
Earlier, the Irish Hospital Consultants Association and the Irish Medical Organisation defended their record of cooperating with change.
They claim that they have brought about savings of €63m and 70,000 bed days in hospitals.
They have accused the HSE of not giving enough time to negotiate such complex issues, some of which they claimed were outside the Croke Park Agreement.
