Royal Bank of Scotland has apologised after NatWest, Ulster Bank and RBS customers were locked out of online and mobile accounts.
Users on Twitter began reporting issues in the early hours of Friday, saying they were unable to access the app or online banking services.
RBS confirmed that customers across its three consumer brands were affected by the outage.
It assured that users were still able to use its telephone banking service and ATMs.
In a statement, RBS said: “We are aware that customers are currently experiencing issues logging into their online and mobile banking accounts.
“We would like to apologise for the inconvenience.
“We are aware of the problem and are working to fix the issue. Customers can still use ATMs and telephone banking.”
Customers hit out at the banks on Twitter, with one saying: “Natwest app down again. Not really acceptable for our 24 economy! How can we trust you with our money?”
The glitch came a day after some Barclays customers were left struggling to log into accounts due to a technical problem.
Barclays said it has since fixed the issue.
The latest banking problems follow TSB’s huge IT meltdown earlier this year, after a botched IT switch saw millions of customers locked out of accounts.