"Currently, the airlines of the Lufthansa Group are affected by an IT outage. This is causing flight delays and cancellations. We regret the inconvenience this is causing our passengers," Lufthansa said on Twitter.
Later in the day, Lufthansa spokesperson told German newspaper Handelsblatt that the malfunction had appeared after a critical cable had been damaged during construction work at Deutsche Telekom's network in Frankfurt Airport, which serves as the airline's main hub in Germany.
Apart from Frankfurt, the airline's system was also shut down in Munich and other airports around the globe. Lufthansa's network airlines Eurowings, Austrian, Brussels and Swiss faced difficulties in their work as well.