Planes were gradually taking off again Saturday (Jul 20) after global airlines, banks and media were thrown into turmoil by one of the biggest IT crashes in recent years, caused by an update to an antivirus programme.

Passenger crowds had swelled at airports on Friday as dozens of flights were cancelled after an update to a programme operating on Microsoft Windows crashed systems worldwide.

By Saturday, officials said the situation had returned virtually to normal in airports across Germany and France, as Paris prepared to welcome millions for the Olympic Games starting on Friday.

Multiple US airlines and airports across Asia said they had resumed operations, with check-in services restored in Hong Kong, South Korea and Thailand, and mostly back to normal in India, Indonesia and at Singapore's Changi Airport as of Saturday afternoon.

"The IT systems in Singapore organisations affected by the global outage are almost fully recovered," said Minister for Digital Development and Information on Sunday morning.

Mrs Josephine Teo said the incident left many feeling vulnerable and questioning the heavy reliance on technology for everyday activities.

She acknowledged the validity of these concerns and laid out the preparatory work taken by Singapore during "peacetime" in anticipation of such incidents.

Stress-testing is done through regular tabletop exercises, she said, adding that many organisations also have business continuity plans.

"Let's continue to learn as much as possible from the incident to strengthen our digital resilience. Only by doing so, can we emerge stronger together," she wrote in a Facebook post.