Customers of the Santander bank have been unable to access their accounts via other app or online on Monday morning, with problems paying by card as well.
People have taken to social media to report being unable to check on or access their money at the start of the week.
Santander UK tweeted: "We’re aware that some customers are experiencing issues accessing mobile and online banking and making card payments.
"We’re sorry for the inconvenience and working hard to fix the issue as soon as possible."
On the Santander site, the company reports: "We're sorry that a technical problem is affecting our Online and Mobile Banking services. Our teams are working hard to fix the problem."
It adds: "We are aware that some customers are currently experiencing issues with card payments and as a result our phone lines are very busy. We apologise for any inconvenience and are working hard to resolve this as soon as possible."
