ULSTER Bank is to cut its workforce by 950, with 600 redundancies here and 350 in Northern Ireland.
And it has not ruled out compulsory redundancies but this will depend on how many staff sign up to leave the bank.
Management and unions will meet tomorrow to discuss the losses.
The bank, a subsidiary of the Royal Bank of Scotland (RBS) which has announced 3,500 lay-offs in its investment wing, said it needed to reduce staff levels to compete in the financial sector.
In a statement, the bank said: "As local and global economies continue to deteriorate, these actions are being taken as part of the bank's overall business strategy to ensure the organisation is well placed to compete effectively in the market and continues to serve the needs of its 1.9 million customers across the island of Ireland through its extensive branch and business centre network."
It is the second major wave of job losses at the RBS division in Ireland after it announced 1,000 redundancies in 2009.
Ulster Bank executives held meetings with trade union representatives from the Irish Bank Officials Association (IBOA) in Belfast yesterday.
Staff were notified of the scale of the losses through messages on the company intranet as they arrived for work this morning.
Larry Broderick, general secretary of IBOA finance union and representing 3,500 workers, said the impact of the latest round of cuts could be even more severe than the cuts in 2009.
"The sheer magnitude of this second wave of proposed redundancies is breathtaking," he said.
Mr Broderick said he wants answers on how the cuts will help the bank's declared commitments on enhanced services to customers which were promoted in recent ad campaigns.
The IBOA said it will seek clarification from Ulster Bank's parent, RBS, on its commitment to Ireland.
"Our members feel very strongly that Ulster Bank staff are continuing to suffer for the mismanagement, incompetence and greed of senior management in Ulster Bank's parent company, RBS, which has been nationalised in all but name, as a result of the biggest collapse in British corporate history," Mr Broderick said.
RBS has been refinanced with £45.5 billion of British taxpayers' money.
"While those responsible have escaped with impunity - through golden parachutes and the like - and while those charged with restoring the fortunes of RBS are apparently due to be handsomely rewarded with generous bonuses, the ordinary staff throughout RBS have been called upon to bear a disproportionate amount of the pain," Mr Broderick said.
"In Ulster Bank too, rank-and-file staff are again being asked to make the lion's share of the sacrifices being demanded to restore the bank to health."
Ulster Bank, although a major player and loser in the Irish property boom and bust over the last decade, is not part of the Irish Government's bank bailout scheme or the bad-bank recovery plan through the National Asset Management Agency (Nama).