Card payments system crash disrupts shoppers
Thousands of afternoon shoppers in the UK were unable to pay by credit or debit cards when a computer problem affected processing systems.
Sainsbury's, Waitrose, Homebase and B&Q were among stores hit on Saturday.
Sainsbury's said its 872 stores had been affected for about 20 minutes. B&Q and Waitrose said most payments were completed using back-up facilities.
Barclaycard, one of the firms operating payment terminals, apologised and said it had had a "technical issue".
"For about an hour this afternoon we experienced a technical issue that meant card payments could not be made in some large retailers," the company said in a statement.
"We would like to apologise for any inconvenience caused by this issue and we are conducting a thorough investigation into the cause of this issue."
B&Q said it had manual card payment equipment at its 330 stores and had been able to deal with the transactions that way.
Waitrose said its problems began in petrol stations before spreading to supermarket branches. It was able to deal with 95% of payments via the back-up system.
Home Retail Group, which owns Homebase and Argos, said its stores had experienced problems for an hour.
"We are talking to service providers to understand the cause," it added.
A number of different financial companies run card payment IT systems for stores in the UK. It is understood not all systems were affected.
Barclaycard told the BBC it had had problems between 1412 and 1430 on Saturday, which resulted in some cards being declined.
It would not divulge which of its customers were affected but Waitrose has confirmed it does use the company to process payments.
Visa Europe said it had experienced no problems with its systems.
Industry group UK Payments says about £11-12bn is spent on credit cards per month in the UK, and £24bn is spent on debit cards.
On Twitter, the micro-blogging social network site, dozens of users reported the problem.
"Saturday afternoon in Sainsbury's. All card payments down. Chaos!" tweeted one user.
Another reported: "Sainsbury's on a Saturday - bedlam!"
BBC website readers have also been sharing their experiences.
Shirley from Rochford, Essex, said of the difficulties at her local branch of Homebase: "Most people realised it was out of the shop's control but a few customers were less than polite over the matter."
Meanwhile, Greg, from Bangor, County Down, said: "Argos stores are the same - no card payments. Saturday afternoon hell."
Tesco said that, despite rumours, it had had no reports of problems with its payments system.