Flights in and out of Scotland, Northern Ireland and the north of England were disrupted Monday due to an air traffic control failure, the latest embarrassment to afflict the U.K. national air traffic controller.

Although NATS, formerly known as National Air Traffic Services, said the issue at its Prestwick center in Scotland has been fixed, the repercussions would likely continue through the day at the very least, with flights canceled or delayed.

"We are working with airports and airlines to safely lift air traffic regulations as quickly as we can to minimize any further disruption," it said in a statement. "We apologize for the disruption."

NATS said airports south of Manchester, including those in and out of London, are "broadly unaffected."

Manchester, Belfast International, Edinburgh and George Best Belfast City airports have seen the most disruption, according to aviation analytics company Cirium.

NATS said the disruption is unconnected with the software glitch that led to the cancellation of over 2,000 flights in and out of the United Kingdom two weeks ago. The chaos prompted mounting calls for its chief executive Martin Rolfe to stand down.

In a report on the outage published Friday, NATS said a software defect in the National Airspace System, which allocates codes so air traffic controllers can identify flights on radar, was behind the decision to ax the flights.

A previous outage in August 2023 cost airlines 100 million pounds ($134 million) and caused travel chaos.

Airlines and airports were aghast at the latest problem to afflict air traffic control over the U.K.

Ryanair, Europe's biggest airline, ​said 25,000 of its passengers were facing delays as a result of Monday's ​issue and repeated its calls for Rolfe to resign.

"Martin Rolfe has presided over repeated system failures, repeated passenger disruption and repeated failures to deliver an effective back-up system," its chief operations officer Neal McMahon said. "Enough is enough. Martin Rolfe should resign today."

Rival airline easyJet had to cancel some ‌flights, saying the latest disruption "once again calls into question the resilience of NATS' systems and demonstrates the need for firm actions to prevent these repeated failures."

And British Airways said it is "disappointing" that some customers may experience disruption after "yet another technical fault" involving NATS.

The U.K. government owns 49% of NATS, making it the largest shareholder and giving it a veto over key decisions. Airlines, airports, investors and employees own the remaining shares in the public-private partnership.

"I know this will be deeply frustrating for passengers after the previous issue," Transport Secretary Heidi Alexander said.