No planes can currently take off and land in Switzerland.
The reason for this is the failure of the Skyguide computer system, which monitors Swiss airspace and the adjacent airspace.
The company announced on Wednesday morning that Swiss airspace was closed.
It was not finally clear when the problem would be fixed.
Apparently all airports in the country are affected by the failure, including Geneva, Zurich, Bern and Basel.
The airport operator in Geneva initially announced on Twitter on Wednesday morning that no landings and take-offs could take place until 8 a.m.
Air traffic is now suspended until 11 a.m.
In Zurich, at the country's largest airport, the planes have to remain on the ground for the time being.
A picture was circulated on Twitter showing a flight board.
Accordingly, all flights are affected.
More information would be shared later.
Passengers complained on Twitter that they had already been guided through check-in and were now stuck at the airport.
No take-offs and landings at Swiss airports were observed using the Flightradar24 tracking tool either.
There, several planes were waiting at the airports for their onward journey.
So far it is unclear what impact the computer failure and the delays will have on European air traffic.
Aviation is currently under pressure anyway because there is a shortage of staff at the airports.
Lufthansa alone had announced that it wanted to cancel hundreds of flights in the summer in order to relieve airports.