The fast food chain said stores in Australia were also reopening after systems froze and orders could not be taken, while some branches in Japan were reportedly resuming trade too.

Problems started in the early hours and continued throughout the morning.

McDonald’s said the issue was unrelated to cyber-security but would not say how many stores had been affected.

“We are aware of a technology outage which impacted our restaurants. The issue has now been resolved in the UK and Ireland,” the company said in a statement.

“We thank customers for their patience and apologise for any inconvenience this may have caused.”

Sarah McLean, who owns a franchise across the Midlands, said that all of her 21 branches had been affected.

“My restaurants were impacted very early in the morning, so thankfully the impact wasn’t too significant, about an hour and a half,” she told the BBC. But during that time they “couldn’t serve anyone”.

Downdetector, a system used to monitor IT problems in businesses, noted a spike in issues with the McDonald’s UK app from around 05:00 GMT on Friday.

Some social media users posted their discontent.

“@McDonaldsUK why can I order through the app this morning but all of my local McDonald’s are closed when they are meant to be 24 hours?!” Tom Bennison in the East Midlands posted on X, formerly Twitter.

Andrew Evans in Birmingham posted: “Hmmm @McDonaldsUK my local is turning everyone away saying there’s a national outage on your ordering system?”

Problems were reported in several countries, including New Zealand, Austria and Germany, but come the afternoon they were starting to get resolved.

Japanese news agency Kyodo reported that stores across Japan were beginning to resume operations following the system disruption.

McDonald’s in Japan had earlier said: “There is currently a system failure. We apologise for any inconvenience this may cause and ask that you please wait for a while until the service is restored.”