A widespread Microsoft Azure outage took out critical services around the world, at the same time as a faulty CrowdStrike update brought down Windows PCs.

The cloud company said that the Central US region was now back online after more than five hours of downtime - although customers may take longer to resume services.

Cybersecurity software firm CrowdStrike said that an update it released was accidentally causing blue screen of death error screens.

The timing of the two seemingly unrelated outages has made it hard to ascertain which one has led to the following service disruptions, or if it is a combination of both. More appear to be attributed to the CrowdStrike failure.

The outages led to some airlines grounding flights, including Frontier, American, and United Airlines. Melbourne airport told customers it was “experiencing a global technology issue which is impacting check-in procedures for some airlines.”

The UK's Thameslink Railway's brands - Southern, Thameslink, Gatwick Express and Great Northern - also said that services were disrupted by the outage, as did the NHS health service.

Microsoft services including Xbox Live and Microsoft Teams were down for several hours.

Australian banking apps and supermarket systems were also impacted by the outage. Sky News in the UK and Australia was also unable to broadcast live.

Telecoms firm Telstra said that both the Microsoft and Crowdstrike outages were disrupting services.

“Our entire company is offline," one IT admin said on Reddit, blaming the CrowdStrike update. CrowdStrike has rolled back the update, but it doesn't help those already impacted.

CrowdStrike CEO George Kurtz said: "CrowdStrike is actively working with customers impacted by a defect found in a single content update for Windows hosts. Mac and Linux hosts are not impacted. This is not a security incident or cyberattack. The issue has been identified, isolated and a fix has been deployed.

"We refer customers to the support portal for the latest updates and will continue to provide complete and continuous updates on our website. We further recommend organizations ensure they’re communicating with CrowdStrike representatives through official channels. Our team is fully mobilized to ensure the security and stability of CrowdStrike customers."

In a status update, Microsoft said: "A backend cluster management workflow deployed a configuration change causing backend access to be blocked between a subset of Azure Storage clusters and compute resources in the Central US region. This resulted in the compute resources automatically restarting when connectivity was lost to virtual disks.

"Mitigation has been confirmed for all Azure Storage clusters, the majority of services are now recovered. A small subset of services is still experiencing residual impact. Impacted customers will be continuing to communicate through the Azure service health portal."

We will update this story as we learn more.