Payments firm Visa has said it is "operating at close to normal levels" after a service disruption in Europe blocked transactions and left some customers unable to use their cards.
Visa said it had experienced disruptions that were preventing some transactions in Europe from being processed on Friday. Millions of people across Europe found themselves unable to use their cards.
Most of the problems appeared to be with chip and pin transactions at the point when a message was sent back from Visa to the card to confirm payment.
Customers in Britain, Ireland and other European countries reported being unable to use their Visa credit and debit cards. Cards belonging to Visa's rivals, American Express and Mastercard, were not affected.
By late Friday, banks and card machine providers said Visa had corrected the outage and transactions were starting to go through, with some delays due to a backlog of transactions.
"Visa cardholders can now use their Visa cards as we are currently operating at close to normal levels," the company said in a statement.
"The issue was the result of a hardware failure. We have no reason to believe this was associated with any unauthorized access or malicious event."
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Some customers at a clothing store on Berlin's Alexanderplatz waited up to 20 minutes to pay, with staff unable to say why the transactions failed to go through.
amp, jm/cmk (AFP, AP, dpa, Reuters)