Union representatives are meeting with management at Ulster Bank amid fears that more than 500 job losses at the bank will be announced tomorrow.
The bank said this afternoon that it did not comment on speculation.
A spokesperson said: "Announcements pertaining to jobs are made to staff directly."
Irish Bank Officials Association General Secretary Larry Broderick said: "We have been concerned about speculation about job losses. We want Ulster Bank to clarify the situation."
Speaking later on RTÉ's Drivetime, Mr Broderick said he believed tomorrow would be an appalling day for staff at Ulster Bank.
The bank currently employs 6,000 in total on both sides of the border. It made 1,000 staff redundant in 2009.
The bank was heavily exposed to the commercial property sector, including funding Sean Dunne's purchase of Jurys Ballsbridge Hotel at the height of boom.