Natwest bank, a subsidiary of the Royal Bank of Scotland (RBS), is currently trying to resolve fresh technical problems with its online banking and debit cards.
This will be unwelcome news for the bank's customers who experienced weeks' worth of problems after a major IT failure on RBS' systems.
Millions of RBS customers couldn't gain access to funds in their bank accounts after a botched upgrade that was made to batch processing software CA 7 from CA Technologies.
It was revealed that it was RBS' Edinburgh-based IT staff that were responsible for the systems failure, which contradicted earlier media reports that claimed a junior IT worker based in India had made the error.
Some customers of Ulster Bank, a subsidiary of RBS' in Ireland, were still experiencing problems over a month after the failure occurred.
A spokeswoman at RBS confirmed the latest Natwest difficulties to Computerworld UK.
She said: "Some of our customers are experiencing technical difficulties this afternoon with online banking and debit cards. We are working hard to resolve this and will provide an update as soon as possible."
This news comes as City regulator the Financial Services Authority prepares to tell UK banks to upgrade their outdated IT systems in light of RBS' failure. It is also reportedly going to be dealt a fine worth tens of millions of pounds.
Nationwide bank customers, some 704,426 accounts, have also experienced difficulties this week as the bank charged debit card transactions twice for payments made on Tuesday 24 July. However, a statement from the bank said that this was down to "human error" and customers will be reimbursed in full.