Millions of customers frustrated by a glitch which shutdown NatWest's online and mobile banking services have been told the fault has "been resolved".
NatWest, RBS and Ulster Bank customers were left unable to pay bills or view their balance after being locked out of their online and mobile accounts following an error that occurred in the early hours of Friday.
A statement from the bank said: "We would like to apologise to customers who experienced issues logging into their online and mobile banking accounts this morning, this issue has now been resolved."
Users on Twitter began reporting issues saying they were unable to access the app or online banking services.
The group has 19 million customers in the UK and Republic of Ireland and 5.5 million active mobile app users according to the RBS annual report.
RBS confirmed that customers across its three consumer brands were affected by the outage, but said users were still able to use its telephone banking service and ATMs.
However, customers have tweeted reporting problems with getting cash from ATMs.
In an interview with LBC Chief Executive of RBS, Ross McEwan said the problem with the online and mobile banking services could be linked to the bank's changes to "technologies" but explained that he doesn't know what the exact root of the problem is.
He added: "Last week we launched out a new range of activities that customers can do on their mobile, that they loved.
"A whole raft of things that they can stop and start using their cards, if they lose their cards they can go on and stop.
"All these things run through our systems ... and every so often we do have difficulties".
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."
The glitch came a day after some Barclays customers were left struggling to log in to their 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.