Payment network Visa has confirmed that it has been disrupted by a service outage.
The company said the disruption is preventing some Visa transactions in Europe from being processed.
"Visa is currently experiencing a service disruption. This incident is preventing some Visa transactions in Europe from being processed. We are investigating the cause and working as quickly as possible to resolve the situation," the company told ZDNet.
The Nationwide Building Society told customers that it had been advised by VISA that a problem was causing some card payments to be incorrectly declined online and in-store. UK bank NatWest said it was also looking into reports of card payments being declined.
On Twitter HSBC told customers that there had issues with Visa's payments processing but said: "From what we understand there are still intermittent issues but services are slowly recovering."