RTX, Collins Aerospace's parent, said it had become aware of a "cyber-related disruption" to its software in select airports, without naming them.

"The impact is limited to electronic customer check-in and baggage drop and can be mitigated with manual check-in operations," the company said in an e-mailed statement, adding that it was working to fix the issue as quickly as possible.

The attack has rendered automated systems inoperable, allowing only manual check-in and boarding procedures, Brussels Airport said on its website, adding the incident had occurred on Friday night.

"This has a large impact on the flight schedule and will unfortunately cause delays and cancellations of flights...The service provider is actively working on the issue and trying to resolve the problem as quickly as possible."

Passengers with a flight scheduled for Saturday were advised by the affected airports to confirm their travel with airlines before heading to the airport.

"Due to a technical issue at a system provider...there are longer waiting times at check-in. We are working on a quick solution," Berlin Airport said in a banner on its website.

Frankfurt Airport, Germany's largest, was not affected, a spokesperson said. An official from the operations control centre at Zurich Airport also said it had not been impacted.