Chancellor Angela Merkel told Turkey to stop invoking Berlin's Nazi past in criticizing cancellations of Turkish ministers' rallies in Germany, and said she would do everything possible to prevent Turkish domestic conflicts spilling onto German soil.
Turkish President Tayyip Erdogan, who survived an army attempt to topple him in July, is working to enlist the votes of Turks abroad to clinch sweeping new powers in an April referendum. But unease is spreading in Europe over the dispatch of ministers to communities themselves sometimes deeply divided.
“To the many people with Turkish roots who are German citizens or have lived here for a long time, I say: you are part of our country," Merkel said on Thursday.
"We want to do everything we can to make sure that possible internal Turkish conflicts are not carried over into this life together (here).
"Let us support our way of life together and even improve it where possible. That is a matter of the heart."
Some took a harsher line than Merkel. Andreas Scheuer, head of her CSU Bavarian sister party, said “the campaigner Erdogan and his henchmen" were not wanted in Germany.
The dispute over cancellations has become entangled with other tensions between Turkey and its NATO allies.
West European politicians have accused Erdogan of using the coup as a pretext for mass arrests and dismissals that stifle dissent. Erdogan, for his part, accuses European powers of racism, harboring enemies of Turkey, including Kurdish militants, hardline leftists and people linked to the July coup.
Scores of Turks, including diplomats and army officers, have applied for political asylum in Germany, Greece, Switzerland and other countries.
Merkel spoke unusually bluntly in the Bundestag lower house of parliament, calling for the release of a German-Turkish journalist being held in a Turkish prison. She said she was saddened by deep differences between the allies.
Erdogan's references to Germany's Nazi past were, however, "so misplaced that you can't seriously comment on them".
"These comparisons of Germany with Nazism must stop. They are unworthy of the close ties between Germany and Turkey and of our peoples," she said.
Turkey's Foreign Minister effectively repeated the comparison within hours.
"We are not calling the government Nazi. Its practices recall that era," NTV television quoted Mevlut Cavusoglu as saying.
Austria has proposed an EU-wide ban on Turkish referendum rallies.
Cavusoglu said on Thursday he would not succumb to "fascists and racists" like Dutch nationalist politician Geert Wilders, who has called for a ban on Turkish rallies in the Netherlands.
"I will go to the Netherlands, no such obstacle can stop us," Cavusoglu told reporters.
Cavusoglu's comments contradicted earlier reports that he had canceled a Rotterdam rally.
The Swiss government said on Thursday it was reviewing a request by financial capital Zurich to block a planned weekend appearance by Cavusoglu for security reasons.
The Hilton hotel booked for the rally canceled the event, saying organizers could not ensure the safety of guests and visitors.
Erdogan, a divisive figure but by far Turkey's most popular leader, says the strong presidency is vital to a country threatened by Islamist and Kurdish militant attacks and dogged by a history of unstable coalition governments.