Stores in London, Manchester, Cardiff and Glasgow, including others, were affected. Some shops were still accepting payment through mobile apps and cash.

“We have now resolved the technical issue that affected tills in some of our shops earlier this morning,” a Greggs spokesperson said. “The majority of shops affected are now able to take card and cash payments again and we expect the issue to be fully resolved shortly. We apologise for the inconvenience this may have caused to our customers.”

Sainsbury’s and Tesco were also faced with an IT outage over the weekend, disrupting customers ability to pay through card and contactless.

Ryta Zasiekina, Founder of CONCRYT said: "The recent widespread IT issues impacting major retailers like McDonald’s, Sainsbury’s, Argos, and Tesco, which resulted in disruptions to contactless payments this weekend, is concerning for the payments industry. While the companies involved have attributed the problems to technical issues, there’s also speculation about potential cybersecurity attacks. This has fuelled various conspiracy theories on social media, highlighting concerns about the risks associated with a cashless society. Such events not only undermine businesses but also cause significant disruption. It’s a stark reminder of the importance of offering diverse payment methods to ensure continued revenue generation in the event of card system failures or other unforeseen circumstances."

Andrew Martin, founder of SMEB said: “The card payment issues experienced by some of the UK’s largest businesses over the past week have shone a fresh light on the continued importance of cash in today’s society. It is the latest sign that the march to a completely cashless society is a bad idea.

“Millions of customers still recognise that cash is a convenient and secure payment method, and they like that it won’t simply disappear – even if your internet reception does."