BERLIN (Reuters) – Germany’s air traffic control (DFS) said on Thursday it had reduced air traffic volumes in large parts of the country due to a software problem in its control centre near Frankfurt.

The affected area stretches from Lake Constance on the Swiss border to the city of Kassel in central Germany and includes Frankfurt, Cologne/Bonn, Stuttgart and Duesseldorf airports, DFS said.

“Aviation safety is not affected,” DFS said on its website.

(Reporting by Thomas Seythal; Editing by Michelle Martin)