Hundreds of Lloyds Bank, Halifax and Bank of Scotland customers have been locked out of their accounts thanks to a problem affecting the banks' online services and mobile apps.
The lenders, all owned by Lloyds Banking Group, confirmed the issue on their Twitter accounts at around 11.30am BST.
As of 3.30pm BST, the banks had not provided any update on a resolution or the cause of the problem.
In response to customers on Twitter, Lloyds says it does not "currently have a timescale for when this is going to be fixed".
According to the Downdetector site, customers began reporting problems at around 10.00am, with the issue appearing to affect customers across the country.
Frustrated customers have been sharing their stories on social media:
Lloyds has closed dozens of branches this year, citing the rise of mobile and online banking.
Update:
Lloyds tweeted that services are back to normal at 9:43pm, more than 10 hours after the issue began.