Ulster Bank has refused to rule out compulsory redundancies for its staff.
The bank announced this morning that 950 jobs were being cut from its Irish workforce by the end of the year.
Six hundred jobs are going in the Republic, while 350 are being lost in the North.
Ulster Bank, a subsidiary of the Royal Bank of Scotland (RBS) which today announced a separate 3,500 job cuts in its investment wing, claimed it was taking the drastic action to remain competitive.
The bank said it hoped to secure the redundancies on a voluntary basis, but did not rule out compulsory cuts.
There are no plans to close branches, but the bank said the network was under constant review.
Jobs Minister Richard Bruton said: "We feel for the families of the workers. This is a serious blow for them. The resources of the State will be there to support them in whatever way we can."
IBOA general secretary Larry Broderick said: "The first objective is to maximise the number of jobs being retained.
"Secondly, we need to agree terms. There have been terms in the past, and we expect those to be on the table again."