Customers in several large retailers across the UK were left unable to pay for goods using credit and debit cards last weekend following problems with Barclaycard's payment system.
Barclaycard has blamed a "technical issue" with its electronic fund transfer (EFT) system for failed card transactions on Saturday 2 October, which reportedly left hundreds of customers unable to make electronic payments in retailers such as Sainsbury's.
Barclaycard is currently conducting an investigation into the cause of the issue.
"For just under half an hour on Saturday afternoon we experienced a technical issue that meant card payments could not be made in some large retailers," said a spokesman for Barclaycard.
"We have established that the issue was caused by a systems error which impacted the ability to authorise transactions."
Both Waitrose and Sainsbury's experienced problems conducting card payments.
Waitrose said it encountered problems processing any Electronic Fund Transfer cards with Barclaycard system processing. Its in-house back-up system ensured 95% of transactions could be processed.
A spokesman for Sainsbury's said, "Many retailers across the country were affected by an issue with card payment systems over the weekend. The problem was rectified very quickly and all of our stores are now trading normally."
Barclaycard said steps have been taken to ensure that the issue cannot reoccur.
This is the second glitch for Barlcays in recent months. A systems crash at Barclays in August this year meant thousands of UK customers were unable to access their bank accounts or withdraw money from cash machines.