The ATGWU is advising its 20,000 Irish members to reject the Government's latest pay offer.
The union's executive regional committee for Ireland has been discussing the proposal for a successor to the Programme for Prosperity and Fairness (PPF).
The Amalgamated Transport and General Workers' Union says the proposed increase of 7% phased over 18 months barely covers inflation.
The union believes it amounts to the Government asking its members to take a pay cut.