NatWest has been hit by a ‘cyber attack’, leaving customers unable to access online accounts.
The bank’s online banking service was disrupted after it was deliberately bombarded with internet traffic.
Twitter users tweeted to say they could not access their bank accounts to pay bills or transfer money.
@TomGilchrist wrote: “Do other banks computer systems/services go down as much as NatWest? I assume not. Time to move banks I think.”
@AleexReid tweeted: “Just joined Santander. Fed up with NatWest. Another computer failure tonight. #welldone.”
A NatWest spokesperson said: “Due to a surge in internet traffic deliberately directed at the NatWest website, some of our customers experienced difficulties accessing our customer web sites this evening.
“This deliberate surge of traffic is commonly known as a distributed denial of service (DDoS) attack.
“We have taken the appropriate action to restore the affected web sites. At no time was there any risk to customers. We apologise for the inconvenience caused.”
At the beginning of December all of RBS and NatWest’s systems went down for three hours on one of the busiest shopping days of the year.
The group chief executive Ross McEwan described that glitch as “unacceptable” and added: “For decades, RBS failed to invest properly in its systems.
“We need to put our customers’ needs at the centre of all we do. It will take time, but we are investing heavily in building IT systems our customers can rely on.”
RBS and NatWest also came under fire in March after a “hardware fault” meant customers were unable to use their online accounts or withdraw cash for several hours.
A major computer issue in June last year saw payments go awry, wages appear to go missing and home purchases and holidays interrupted for several weeks, costing the group £175m in compensation.
This latest problem is the fourth time in 18 months RBS and NatWest customers have reported problems with the banks’ services.