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

Several airlines have grounded flights around the world and many more are reporting delays.

The US state of Alaska has warned its emergency services are affected, supermarkets in Australia have been crippled, and media outlets in several countries have been left scrambling as systems failed, with Sky News in the UK temporarily forced off air.

The cause of the outage is unclear, but many of those impacted have linked it to Microsoft PC operating systems.

An official Microsoft 365 service update posted to X earlier in the day said "we're investigating an issue impacting users ability to access various Microsoft 365 apps and services".

However, a Microsoft spokesperson told the BBC on Friday that "the majority of services were recovered" hours earlier.

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.

Social media users have reported problems making payments at stores like bakery and coffee chain Gail's in the UK and grocer Woolworths in Australia, and also trouble accessing financial institutions like the National Australia Bank.

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

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. Other airports - including in Berlin, Tokyo and Dehli - are also impacted.

In the UK, Govia Thameslink Railway warned passengers to expect disruption, while Black and White Cabs in Australia said their systems had been impacted too.