Windows PCs and computer systems using Microsoft software have been hit by the outage, which has affected companies worldwide inclduing airlines, banks and software providers, and even RNS feeds from the London Stock Exchange.

The issue was caused by problems with a cybersecurity update to Falcon Sensor software by Crowdstrike, which has resulted in a blue screen error appearing on computers. Screens go blue and a message comes up stating that 'your PC ran into a problem and needs to restart. We're just collecting some error info, and then we'll restart for you'.