The global IT outage has caused disruption across the UK, including to healthcare and transport.

GPs have been struggling to access their records systems, which include online bookings. Pharmacy services, such as access to prescriptions, have also been affected.

The outage has led to long queues at UK airports and knocked some TV channels off air.

Cyber security firm Crowdstrike said the global IT problems were caused by a defect in a content update and were not due to a security incident or cyberattack.

“The issue has been identified, isolated and a fix has been deployed,” said George Kurtz, CEO of Crowdstrike.

Cabinet Office Minister Pat McFadden said the global outage was not a security attack or a hostile act.

He said: “The cause appears to be a software error in an update … a fix is being put in place.”

“We’re very conscious that people are still being inconvenienced of this, not just here in the UK, but in many other countries too.”

The NHS said it was aware of the global outage and of issues with its EMIS system, which many GPs use to manage appointment bookings, conduct patient consultations, and update, store and share patient records – including sending prescriptions to pharmacies.

“Patients should attend appointments unless told otherwise. Only contact your GP if it’s urgent, and otherwise please use 111 online or call 111,” an NHS spokesperson said.

They added there was no known impact on 999 or emergency services.

The National Pharmacy Association confirmed the issue was affecting community pharmacies, “including the accessing of prescriptions from GPs and medicine deliveries”.

Professor Kamila Hawthorne, chair of the Royal College of GPs, said the outage was of “serious concern” and asked people to be patient as clinics worked to keep services going.

Northern Ireland’s devolved government said around two thirds GP surgeries had been affected and would only be taking emergency appointments until the issue was resolved.

Dr Jess Harvey, a GP in Much Wenlock, Shropshire, told the BBC that her surgery had been able to access a “really primitive version” of EMIS, but could not access blood test results and had cancelled some routine appointments.

She said that doctors were still able to issue prescriptions “the old fashioned way” with handwritten notes.

“We’re working really hard as a team to try and get through it,” Dr Harvey added. “I’m sure that’s the same in GP practices across the country.”

Neha, from Ashford in Kent, was among patients affected. She told the BBC that the blood test she had booked a month ago had been cancelled this morning.

She was told by her GP surgery that they could not access some of their computer systems and would get back in touch to rebook the blood test.

“I was waiting for this test and now I have to wait again,” Neha said.

The outage has also affected travel infrastructure across the UK.

Long queues have been reported at airports. British Airways said some flights were “likely to experience disruption”.

The UK’s largest airport, Heathrow, said the outage was affecting “select systems”.

“Flights are operational and we are implementing contingency plans to minimise any impact on journeys,” Heathrow said.

Gatwick Airport said e-gates and some check-in systems were being impacted by the problem. Passengers there are reportedly being checked in manually.

Manchester Airport said staff were also processing check-ins and boarding manually. While flights to and from the airport were mostly unaffected, it warned of a potential knock-on effect on flights later in the day.

Among those who were caught up in the delays were members of a hen do heading to Dublin from East Midlands Airport.

Anna Hindmarsh told the BBC that she and five other people due to travel for her sister’s four-day celebration had been left behind after being delayed when their bags had to be checked in manually.

“I’m really disheartened,” Ms Hindmarsh said, adding that they were now struggling to rebook.

Edinburgh Airport said at least 17 arrivals and 24 departures had been cancelled.

A group of American tourists due to travel home to Texas from Edinburgh told the PA news agency that they had been forced to pay more than £5,000 for new flights.

Some flights into the UK have also been disrupted. Jemma Wheeler, 30, said her family of five was stuck at Palma de Mallorca Airport after the IT issue caused delays at check-in.

“We thought it was a quick, two-hour flight and we would be back in no time to enjoy the nice weather at home,” she told the BBC.

Those waiting for their flights are being urged to keep an eye on communications from their airlines and to keep essential items in their carry-on if they check in bags.

Train services are still running, though National Rail has said there were “widespread IT issues across the entire network”, potentially leading to short-notice cancellations.

“Additionally, other key systems, including real-time customer information platforms, are also affected,” it added.

It warned that services operated by Avanti West Coast, Gatwick Express, Great Western Railway, Southern and Thameslink were among those that could see alterations and cancellations.

British TV channels Sky News and CBBC are now both back on air after having been affected earlier in the day.

Additional reporting by Ian Casey, Dan Martin and Aleks Phillips