That is all for our blog on the major outage that has impacted systems worldwide today.

We will continue to cover the ongoing impact of the CrowdStrike defect on the ABC News website.

In the US, airlines are working to restore systems and resume flights.

More than 1,000 flights had been cancelled and 2,000 delayed by 8:30am Friday morning (US eastern time), according to the FlightAware tracking website.

Still plenty of blue screens at Chicago's O'Hare Airport.

Kurtz told Today that the impact of the outage could be felt for 'some time' due to the systems of some of the company's customers still experiencing issues. 

"Many of the customers are rebooting the system, and its coming up and it'll be operational because we fixed it on our end," Mr Kurtz said.  

"And some of the systems that aren't recovering we're working with them.  So it could be some time for some systems that just automatically won’t recover."

Kurtz told Today a "bug" in the CrowdStrike update caused the issue with the Microsoft operating system.

"This system was sent an update and that update had a software bug in it and it caused an issue with the Microsoft operating system," he said.

"We identified this very quickly and remediated the issue, and as systems come back online, as they're rebooted, they're coming up and they're working and now we are working with each and every customer to make sure we can bring them back online.

"But that was the extent of the issue in terms of a bug that was related to our update."

CrowdStrike CEO George Kurtz has appeared on US television network NBC, telling viewers the company was sorry for the impact of the defect on people around the world.

"I want to start with saying we're deeply sorry for the impact that we've caused to customers, to travellers, to anyone affected by this including our company," he told NBC's Today show. 

The UK's National Health Service (NHS) says the outage is causing problems at most doctors' offices across England.

NHS England said in a statement that the glitch was hitting the appointment and patient record system used across the health service.

The NHS said the issue was affecting the majority of family doctors' practices, but was not hitting the 999 number used to call for emergency ambulances.

The regulatory service at the London Stock Exchange has also stopped working but the outage has not affected trading.

Reuters

The Paris Olympics' organising committee says its IT operations have been impacted by the global cyber outage, just a week before the Games are set to begin.

"We have activated contingency plans in order to continue operations," the organising committee said in a statement.

The organisers said the outages had impacted the arrival of some delegations. But they said impact was limited and the outages had not affected ticketing or the torch relay.

Reporting with Reuters and AP

Microsoft says while the underlying cause for the outages has been fixed, a "residual impact" is continuing to affect some Microsoft 365 apps and services.

"We're conducting additional mitigations to provide relief", the company Tweeted.

We've been bringing you images of the long lines at Australian airports following the computing outage today.

Similar images have been seen all around the world as travel ground to a virtual halt in many countries.

The US's Federal Aviation Administration says United, American, Delta and Allegiant airlines have all been grounded by the outage.

As we mentioned earlier, airlines and railways have been affected in the UK and Germany, as well as other parts of Europe.

In India, Hong Kong and Thailand, many airlines were forced to manually check in passengers, while an airline in Kenya was also reporting disruptions.

ABC local radio presenter Andre Leslie was in Kuala Lumpur today, and took images of long lines at the airport with AirAsia's self-service kiosks shut down.

Reuters is reporting that CrowdStrike's Nasdaq-traded shares were down 11.8 per cent in premarket trading early Friday, US time.