A bankers' trade union has said members in First Trust are rejecting plans to change pay, pensions and benefits.
The bank's parent company, Irish state-owned institution Allied Irish Banks (AIB), is in the throes of a massive redundancy programme which will see 2,500 jobs go across Ireland, including 300 north of the border.
Finance union the Irish Bank Officials Association said its members rejected an announcement this month by chief executive David Duffy that staff who remain will face changes to their perks and pension conditions.
A union spokesman said an indicative ballot showed that staff were "virtually unanimous" in rejecting the proposed cut.
IBOA general secretary Larry Broderick said: "This result should provide a wake up call for AIB's senior management and for the Government of the Irish Republic, AIB's predominant share-holder, on the need to engage meaningfully with this union on a fair deal to stay for those staff who will be essential to the future capacity of the bank."
The bank's senior management want to prolong a 2009 pay freeze for at least two more years, reduce pension benefits and remove other benefits for staff.