This afternoon, customers of Barclays bank were unable to withdraw cash from machines or use their online banking service.
The problem, which is thought to have arisen at around 3pm, has resulted in a surge of complaints on Twitter.
In response, Barclays bank posted a tweet letting customers know that they were dealing with the issue.
"We're aware of an issue that is currently affecting some customers when attempting to make card transactions and withdrawals. We are working to resolve this issue as quickly as possible and apologise for any inconvenience this may cause," they said.
A spokesman for the bank has since added that the issue stemmed from a temporary IT glitch in the system, and that all machines should now be working.