A raft of global institutions – including hospitals, major banks, media outlets and airlines – have reported a mass IT outage, affecting their ability to offer services.

International airports including in India, Hong Kong, the UK, and the US have reported issues, and several airlines have grounded flights and reported delays.

Emergency services have also been affected with some hospitals cancelling surgeries and the US state of Alaska warning its 911 system may be unavailable.

Cyber security firm Crowdstrike has confirmed the cause of the worldwide outage was a result of their defective software update for its Microsoft Windows hosts.

“The issue has been identified, isolated and a fix has been deployed,” their statement said, assuring it was not a cyberattack.

“We further recommend organizations ensure they’re communicating with CrowdStrike representatives through official channels,” it added.

Earlier in the day, an official Microsoft 365 service update posted to X said “we’re investigating an issue impacting users ability to access various Microsoft 365 apps and services”.

A Microsoft spokesperson told the BBC on Friday that “the majority of services were recovered” hours earlier.

Meanwhile, companies are scrambling trying to resolve issues with the IT outages.

Many broadcast networks in Australia were scrambling on air as systems failed, while Sky News UK went completely off air as a result of the issues. It is now back on air.

Several supermarkets were also crippled, with payment systems down. Pictures from Australia show Coles supermarket’s self-checkout tills closed.

Hospitals in Germany and Israel have reported disruptions, as well as GP services in the UK.

Travel plans across the globe have also been thrown into disarray, with flight, taxis and rail affected.

Airports across Europe, the US and the global south-east have reported system failures, with many passengers having to “manually” do processes typically done by machine.

Samira Hussain, the BBC’s South Asia correspondent, was at Indira Gandhi International Airport in Delhi, India, for a flight to Kolkata.

“I just manually made my boarding passes and the stickers for our check-in bags were also done by hand,” she said, adding it is “absolute chaos” at the airport.

Hong Kong’s Airport Authority said the outage was affecting some of the global airlines at Hong Kong International Airport, with said airlines switching to manual check-in. Flight operations had not been affected, it added.

Across the US, airlines United, Delta and American Airlines have issued a “global ground stop” on all of their flights, while Australian carriers Virgin and Jetstar have delayed or cancelled flights.

According to aviation analytics firm Cirium, more than 1,000 flights have been cancelled around the world following the outages.

Airports in Tokyo, Berlin and Prague have also been reportedly affected. Switzerland’s largest airport in Zurich has said planes are currently not allowed to land.

A spokesperson for the home affairs ministry in Australia – which has been particularly hard hit – said the outage appeared to be related to an issue at a cyber-security firm, while the country’s cybersecurity watchdog said there was no information to suggest a malicious attack.

“Our current information is this outage relates to a technical issue with a third-party software platform employed by affected companies,” they said in a statement.

Alaskan officials said many 911 and non-emergency call centres were not working properly, but Australian authorities say triple-0 call centres – the main emergency contact in the country – are not affected.