Customers have been left unable to access their accounts, due to an error related to Natwest's online banking system.
According to website DownDetector - which records website failures - the lender's online banking tool has been having problems since around 9am.
Customers on social media have also complained that they've been left unable to access online banking.
"Is bankline down ? Logs in ok but can’t load information? Pls advise," Angus Donald tweeted.
The bank initially responded saying they weren't aware of any issues, but later said it was looking into the issue.
"We are aware of the current issues affecting online banking and Bankline logins. Apologies for any inconvenience caused by this, we are working hard to get this fixed as soon as possible," the bank tweeted.
Angus was also not the only person reporting problems.
"All your main UK web pages seem to be inaccessible. I’ve tried clearing cache , used different browsers etc," Ben W tweeted
When the Mirror checked, we were able to both log in to the app and make payments through it - but it seems there is trouble for some customers with the site.
However, attempts to check on Natwest's service status page to see which systems were affected were frustrated by the page itself being down on desktop and mobile browsers.
Natwest said it didn't know when the issue would be resolved yet.
"We are working on this as a matter of urgency. We do not have any specific timescales as of yet. I am sorry for this," the bank tweeted one of its business customers.
Natwest advised people having problems to try the nwolb.com address.
