Some 80 Ulster Bank branches will have extended opening hours until 7pm for the rest of the week as the bank continues an attempt to clear a backlog in payments.
The backlog - which is affecting more than 100,000 Ulster Bank customers - will not be resolved until the end of the week, the bank has said.
In a statement this evening, Ulster Bank said it was facilitating customers who have experienced delays in receiving salary or social welfare benefits on the production of payslips and identification.
Customers who are unable to get to a branch or an ATM are asked to contact the bank on 1800 205100. They can also take cash out on credit cards interest free, it said.
"We continue to work through the backlog of payments caused by the recent RBS Group-wide technical issue with a view to completing this by the weekend. We once again apologise to customers for the continued inconvenience," it added.
"We confirm that no customer will be out of pocket as a result of this issue. We are also working with the credit reference agencies to ensure that customers’ credit ratings are not impacted."
Customers should check the Ulster bank web site, www.ulsterbank.ie, for branches that are open and for relevant telephone numbers.
The bank said that clearing the build-up of interrupted transactions was "taking significantly longer than expected" and, as a result, customer accounts were not fully operational.
It said the original technical problem was caused by a software upgrade to the payment processing system which was corrupted.
In a statement this evening, the Central Bank said it had been in contact with Ulster Bank to "press the bank to resolve the situation as quickly as possible and ensure that customers are treated fairly".
"At a meeting with Ulster Bank senior management today, the Central Bank emphasised the importance of clear communication and support to consumers," the statement added.
The bank processed more than 110,000 transactions with a value of €500 million over the weekend, and a spokeswoman said most payments involving customers from other banks had now been processed.
Ulster Bank opened branches over the weekend to deal with customer inquiries and received almost 9,000 customer telephone calls, while 11,100 people called into its branches.
Today is the seventh day of disruption.
Separately, National Irish Bank confirmed it experienced a technical issue on its systems this morning. The issue resulted in the online banking service being unavailable for a short time.
"The cause of the problem was promptly identified and back-up systems were immediately put in place. Full service across all systems is now being re-established, with most already back up and running. We apologise to customers for any inconvenience caused during this short period," the bank said in a statement.
