Cybersecurity firm CrowdStrike says “a significant number” of devices that were impacted by a global IT outage on Friday are now back online.

In a social media post, the company – whose faulty security update caused Microsoft Windows computers to crash around the world – added it “continues to focus on restoring all systems”.

Microsoft has estimated that the incident, which is being described as one of the worst IT outages in history, impacted 8.5m computers around the world.

Businesses, banks, hospitals and airlines were among the worst-hit, with some still struggling to fully restore their systems.