Travel chaos could be on the cards with staff at Irish Rail to be balloted for industrial action next month.
It comes after pay talks broke down without agreement at the Workplace Relations Commission last night.
Unions were seeking a pay rise of around 4%, but say the company wants to add a number of conditions.
General Secretary of the NBRU Dermot O'Leary has warned of an all-out-strike.
He said: "It's unfortunate that the people of this country, particularly those who use Irish Rail on a regular basis - commuters and long distance - are going to be disrupted in the very near future, probably the 14th of October."
Mr O'Leary said that as a result frustration levels were now at a stage whereby the NBRU was left with no choice but to move to a ballot of its members for industral action up to and including all-out strike.
He said: "After a decade long pay hiatus, the expectation of a long overdue pay rise for Irish Rail staff has not materialised.
"Our members have looked at colleagues in the Public Transport Sector enjoying pay increases of up to 3.75%, while Irish Rail is thumbing its nose at its own Staff by making a pitiful offer, at a time when passenger numbers and revenue at Irish Rail are at a historical high, is contemptuous to say the least.
"Sadly the senior Management at the State Company have little or no regard for their workers."
Mr O'Leary went on to say the patience of a beleaguered workforce had run out.
He said: "The spectacle of highly paid senior managers being effectively gagged and restricted to offering ‘strings attached’ crumbs to its staff, including the disgraceful caveat of seeking union acquiescence to the closure of rail lines in order to fund a pay rise, has now brought frustration levels to the stage whereby the NBRU is left with no choice but to immediately move to ballot all its members for industrial action up to and including all-out strike, resulting in widespread travel chaos for commuters in the next number of weeks."