Turkey has summoned the German Ambassador in Ankara after a planned speech by its Justice Minister to Turks living in Germany was cancelled.
Bekir Bozdag was due to speak to around 400 people at a campaign event in Gaggenau in South West Germany, but local officials called off the event, citing safety concerns.
In turn Mr Bozdag cancelled a scheduled meeting with his counterpart, and instead returned home.
Amid a chill in relations between the two countries, he suggested the rally was cancelled for other reasons.
He said: “The right of expression and meeting is guaranteed in all democracies by government bodies. Here those rights have been ignored.
“They are ignored when Turkey comes into question. But for terrorist organisations which have been working against Turkey, the door is open still.”
The diplomatic rift comes after Turkey’s Prime Minister Binali Yıldırım appealed to Turks living in Germany to vote ‘yes’ in a referendum that would expand the powers of President Tayyip Erdogan.
It is thought an estimated 1.5 million Turkish citizens are eligible to vote in the April poll.
Bilateral lies have been strained in recent weeks, with German Chancellor Angela Merkel leading calls for the release of a Turkish-German journalist who is being held in prison.
Germans have been protesting about over the arrest of Deniz Yücel, who was held on charges of propaganda and incitement to hatred.