NatWest, RBS and Ulster Bank customers are currently unable to access their accounts online due to a technical error.

The banking group’s app and online platforms have been offline since about 5am on Friday 21st September.

Customers have been greeted with an error message on the app stating that it is “unable to establish a connection”, while the bank’s website displays a message simply explaining that online banking is “temporarily unavailable”.

In a joint statement, the banks said: “We’re aware of some issues on our Digital and Mobile Banking services and are working hard to fix them. Telephone Banking and ATMs are available. Sorry and thanks for your patience.”

However, some customers have been reporting that ATMs are also affected.

Disgruntled customers have been venting their frustration on social media and complaining about the disruption to service, which follows hot on the heels of a similar issue at rival Barclays yesterday.

On Twitter, one customer said: “They can’t even get the little things right. I think it’s time to change banks. The service is appalling as per usual.”

A Natwest customer added: “Some of us have four kids to feed and now can’t access our money, as it’s not just a mobile app. It’s all online services and bank cards at ATMs.”

While an RBS customer quipped: “I can’t access my online account. I’ll just nip into my local branch. Oh, hold on. It was closed down in July.”

There are 19 million NatWest, RBS and Ulster Bank customers in the UK and Republic of Ireland, with 5.5 million active mobile app users.