Angela Merkel, the German chancellor, has demanded the release of a German journalist arrested in Turkey amid calls for her government to block a visit by president Recep Tayyip Erdoğan over the case.

The Turkish government summoned the German ambassador on Thursday to demand an explanation after appearances by two Turkish ministers in Turkey were prevented by local authorities amid widespread public anger at the arrest.

In a considerable hardening of her position, Mrs Merkel said Germany would do “everything in its power” to secure the release of Deniz Yücel, a correspondent for Welt newspaper held on charges of spreading “terrorist propaganda”.

“Deniz Yücel, who is under arrest in Turkey and whose release we are demanding, is in our thoughts,” Mrs Merkel said.

“A free and independent press is part of democracy and must never be questioned,” she said, adding that Mr Yücel “did nothing but do his job”.

Hours later, local authorities in Cologne and Gaggenau, a small town in southern Germany, withdrew permission for political rallies at which two Turkish ministers were due to speak this week.