More than 1,500 reports of issues affecting Revolut services were flagged to platform outage monitor shortly after 08:00 BST on Tuesday.
A spokesperson for the company later confirmed its problems had been caused by a third-party issue but pointed out that “all our customers’ money and data are safe.”
“We’ve been working to fix the issue since it was identified this morning and apologise to anyone affected and for any inconvenience caused,” they said.
Customers of Lloyds Bank, Halifax and Bank of Scotland – all owned by the Lloyds Banking Group – also reported issues affecting some online banking services.
A Lloyds spokesperson did not confirm the cause of issues affecting some of its services, but told the BBC later on Tuesday “we understand the root issues have been resolved, so we expect all our services to be back to normal soon.”
In an update on service health dashboard on Tuesday afternoon that the issues it was dealing with had been “mitigated for most of the customers” and only a small number were believed to be still affected.
The company said it would publish an analysis of the incident once it had completed an internal investigation, and thanked customers for their patience.