The Ulster Bank has announced plans to close around 20 branches and sub offices across both sides of the border this year.
The bank said it would be a number of weeks before it provided details about which outlets would be shutting.
The announcement comes on the back of a troubled 12 months for the Royal Bank of Scotland-owned organisation.
Last January, staff were told that 950 jobs were set to go. In the summer, the bank experienced an IT failure which left hundreds of thousands of customers with limited access to their funds.
The bank faced heavy criticism for its handling of the month-long crisis and the subsequent compensation scheme for those affected. The staff redundancy programme was put hold while the bank dealt with the fall-out from the technological glitch.
There are 146 branches of Ulster Bank in the Republic of Ireland and 90 in Northern Ireland. The new closures are part of the ongoing rationalisation plans. The bank said it would be closing "in the region" of 20 branches and sub offices on the island of Ireland in 2013.
A spokesman added: "We expect to be in a position to provide further details in the next few weeks and will communicate directly with our customers and employees at that time."
The finance union IBOA said it will meet senior management at Ulster Bank next week to discuss the closures, which, it is claimed, a small number workers were told about in a conference call before Christmas.
Larry Broderick, IBOA general secretary, said while branch closures were on the table since last January, this is the first indication of a specific number.
He said: "We are disappointed that the bank's management chose to reveal their intentions in a teleconference to a relatively small number of staff, rather than in the course of the ongoing engagement with IBOA on the restructuring programme."