Public servants say their pay has now fallen behind the private sector on average.
Fresh talks on public sector pay and a replacement for the Lansdowne Road Agreement are due to take place after the Public Service Pay Commission delivers its recommendations to Government.
The Public Service Executive Union (PSEU) - which represents executive grades in the public sector - will be looking for an additional €1.6 billion for civil servants, including €1.4bn in pay restoration.
The claim will be discussed at the PSEU's annual conference in Galway later.
According to the Irish Independent, Government sources have said the projected figure is 'wildly optimistic'.
PSEU General Secretary Tom Geraghty, however, insists that it is realistic to look for the increase - suggesting that it is in fact simply looking to restore "what was taken from public servants".
Speaking to Newstalk Breakfast, he explained: "There's a total of €1.4bn outstanding - that's the value of the pay cuts for public servants. While some lower paid public servants are already out of the infamous FEMPI legislation that imposed the pay cuts, obviously if we do a pay deal we won't be leaving them out - so that's where the €1.6bn comes from."
He continued: "I'm not saying that all is rosy in the garden, but the basis on which public service pay was cut in 2009/10 was that there was a fiscal emergency. Clearly the financial emergency is over.
"All we are seeking - and it's a perfectly reasonable proposition - is to restore what was taken away from us under the guise of an emergency."
He acknowledged that pay restoration will not take place all at once, and noted they will be going into negotiations "with a view to doing a deal that will take place over a period of time".
The issue of pay restoration has also dominated this week's teachers' conferences, with unions calling for equal pay for equal work.
ASTI General Secretary Kieran Christie argued: “We have championed the phrase ‘Equal Pay for Equal Work’. What does this mean for young teachers and others at the start of their careers in the public sector?
"It means starting your career with the expectation that you will be able to access a mortgage, a car loan, childcare; normal every day expectations. For teachers, in particular, it means being treated in a manner consistent with the values of social justice that you teach to your students.”
