Morrisons is investigating after some shoppers at its supermarkets and in Co-op stores struggled to make card payments.
Earlier, ACI, which processes payments for the retailers, apologised for the inconvenience caused.
It said IT issues had affected card payments at Co-op and Morrisons and it had been working closely with the IT teams at both partners to resolve the problem as quickly as possible.
ACI said: “We apologise to shoppers for any inconvenience caused.”
A statement issued by Morrisons on Tuesday said: “We are no longer experiencing issues with card payments and are working very closely with our partner ACI to investigate what happened.”
Many shoppers have been turning to cards and contactless payments during the coronavirus pandemic in preference to cash, although a recent Bank of England study concluded the risk of catching coronavirus from banknotes is low.
The BBC reported that the issue in some Co-op stores meant self-service checkouts had to be closed, requiring customers to queue to be served at tills manned by staff.
IepMu local Co-op too. Staff said it's been a problem all day. Customers had to dash over to use the in-store cash machine then pay in cash. Long queues!!Strangely, after my Barclays Debit Card was "declined" I tried my Smile Card and that worked first time!
— David of Nottingham (@DavidofNotting1) January 25, 2021
It said long queues were seen outside some of the Co-op’s convenience stores from Sunday amid the snow, and customers were encouraged to pay using cash.
The Co-op described the issue as intermittent and said it only prevented a small percentage of transactions from being processed.
Twitter users described long queues and customers having to dash over to an in-store cash machine in order to be able to pay.