FRONTLINE staff claim they face cuts of over 10pc to their income if government plans to deliver €1bn in payroll savings go ahead.
A cut of this size would reduce an average staff nurse's pay by €4,514 a year, while it would hit a garda sergeant by almost €6,000.
The figures were revealed as unions dismissed a government assurance that the savings sought at talks on a new Croke Park deal would be its "last ask" of public servants.
Irish Nurses and Midwives Organisation leader Liam Doran said Public Expenditure Minister Brendan Howlin's promise was "cold comfort" to frontline staff.
However, Mr Howlin hit back and said a deal that protected the premium payments of some staff would be "unfair and unacceptable".
His spokesperson said those who did not get these payments, particularly low and middle earners, could not be expected to carry most of the burden in a new deal.
The row erupted after representatives of 70,000 frontline workers met yesterday to launch a campaign of opposition to cuts to their premium pay and allowances.
The 24/7 Frontline Services Alliance, representing nurses, gardai, prison officers, firefighters and ambulance staff, said they aim to get all cuts to these payments taken off the table.
One garda sergeant said he would "definitely sink" if his €57,000-a-year earnings, which include premium pay and allowances, fell.
"I often walk to work because I can't afford to put petrol in the car," said Tim Galvin, a sergeant in Dun Laoghaire, Co Dublin, who came to the meeting after finishing work at 7am.
He is one of three members of the Association of Garda Sergeants and Inspectors' national executive who is a frontline worker.
"Two of my children are in private schools and one is at third level.
"I have to be earning €24,000 for schooling and another €30,000 for the mortgage.
"If these cuts happen, I'll definitely sink."
The alliance estimates that the cuts being sought would reduce their members' incomes by 10.63pc.
However, many of the unions that make up the Frontline Services Alliance will have no say in a final deal.
Nurses, whose main union is still at the table at talks, will have a vote on any agreement, but gardai and psychiatric nurses do not as they are not members of the Irish Congress of Trade Unions (ICTU).
This does not prevent them carrying out protests, including work-to-rules or blue flu action.
The alliance is meeting next Monday in Tallaght in Dublin to discuss a campaign of protest to the cuts.
Also, the termination of contracts of 10 newly graduated nurses has been condemned by the Irish Nurses and Midwives Association (INMO), as an attempt to coerce them into applying for the lower paid graduate positions.
Management at Kerry General Hospital advised their ten 2012 graduates, who had been employed in the hospital, that their contracts would not be continued beyond February 24, 2013.
Meanwhile, IMPACT, a key negotiator at the talks, has sent a message to members emphasising Mr Howlin and junior minister Brian Hayes's assurances that the Government will not seek more cuts.