SIPTU has spoken out against the controversial top-up salaries being paid to senior executives at some of the country's hospitals.
The union has criticised the payments which in some cases amount to more than €40,000.
A HSE probe into the issue has revealed that the huge figure is being paid by the taxpayer to 191 senior managers in voluntary hospitals and HSE-linked charities across the country.
The probe has raised serious concerns over multiple breaches of the "one job, one salary" policy in place since the 1970s.
It follows revelations of a series of payments to hospital CEOs, including a €30,000 payment to Crumlin manager Lorcan Birthistle from the facility’s tuck shop, and €45,000 paid to Holles St master, Dr Rhona Mahony, who already receives €236,000 a year.
Executives in charge of the National Rehabilitation Hospital (€110,808 salary), the Rotunda (€183,562 salary), and disability service Stewart’s Hospital (€174,928 salary) were also shown to be receiving extra fees.
The Taoiseach has criticised the payments - while the Minister for Health has said those who were paid more than the public sector pay cap would be asked to hand back the cash.
Paul Bell of the health division in SIPTU says the payments are unjust particularly when frontline workers are being asked to take a cut in wages.
"I think that public service workers, be they in health or anywhere else, have had their burden to carry, as has everybody else, in trying to get the country back on its feet," Mr Bell said.
"I don't believe that anybody should be exempt from that, whether they are people who are CEOs of organisations… it just has to be demonstrated that everybody is sharing the burden proportionately."
Meanwhile Minister for Social Protection Joan Burton has said that anyone in a publicly funded position should have regard to government pay structures.
"The critical issue is that these organisation are extensively funded by the taxpayers - they may be organisations with their own structures, but they're funded by the taxpayer," she said.
"I think they have to be accountable, and they have to step in line - if you like - with the sacrifices that other people in the public sector have made."