Major U.S. airlines ordered ground stops on Friday citing communications issues, while other carriers, media companies, banks and telecoms firms around the world also reported system outages were disrupting their operations.

American Airlines, Delta Airlines, United Airlines and Allegiant Air grounded flights less than an hour after Microsoft said it resolved its cloud services outage that impacted several low-cost carriers.

It was not immediately clear whether the call to keep flights from taking off were related to an earlier Microsoft cloud outage.

Microsoft said earlier on Friday that it was gradually fixing an issue affecting access to Microsoft 365 apps and services. Microsoft users worldwide have reported encountering blue screen errors on company computers running Windows.

Microsoft did not immediately respond to a CGTN request for further comment.

In Australia, media, banks and telecoms companies suffered outages, which the government said appears to be linked to an issue at global cybersecurity firm CrowdStrike.

CrowdStrike ran a recorded phone message on Friday when Reuters contacted its technical support, saying it was aware of reports of crashes on Microsoft's Windows operating system relating to its Falcon sensor, without mentioning Australia.

News outlets in the country – including the Australian Broadcasting Corporation and Sky News – were unable to broadcast on their TV and radio channels, and reported sudden shutdowns of Windows-based computers. Some news anchors broadcast live online from dark offices, in front of computers showing blue screen errors.

Crowdsourced website Downdetector showed outages at several banks and telecoms companies.

Australia's National Cyber Security Coordinator said the "large-scale technical outage" was caused by an issue with a "third-party software platform," allaying initial fears of hacker involvement.

The outages rippled far and wide, with Spain reporting a "computer incident" at all its airports, while Ryanair, Europe's largest airline by passenger numbers, warned passengers of potential disruptions which it said would affect "all airlines operating across the network," though it did not specify the nature of the disruptions.

Amsterdam's Schiphol Airport said on its website that the outage was having a "major impact on flights" to and from the busy European hub. The outage came on one of the busiest days of the year for the airport, at the start of many people's summer vacations.

Zurich Airport, the largest in Switzerland, said it had suspended all flight arrivals. "Landings are currently no longer possible," the airport said, though "Flights already en route for Zurich are still authorized for landing."

Amazon Web Services said in a statement that it was "investigating reports of connectivity issues to Windows EC2 instances and Workspaces within AWS."

It was not immediately clear whether all reported outages were linked to CrowdStrike problems or if there were other issues at play.

Beijing Capital International Airport and multiple Chinese airlines told CGTN their operations were not affected by any outage as their operating systems were different.

(With input from agencies)