People wave Turkish flags during a campaigning event with the Turkish Prime Minister in Oberhausen, western Germany in February this year | Sascha Schuermann/AFP via Getty Images Germany slams Erdoğan’s ‘unacceptable’ Nazi comments The Turkish president had likened German cities’ unwillingness to host Turkish campaign rallies to ‘Nazi practices.’

Germany's chancellery rebuked Turkish President Recep Tayyip Erdoğan on Monday for likening a German ban on rallies by Turkish politicians to "Nazi practices," calling the comparison "absolutely unacceptable."

Peter Altmeier, chief of staff to the German chancellery and adviser to Angela Merkel, told ARD Morgenmagazin that while "we also allow people from other countries to make use of freedom of speech in Germany," it had to be done according to the rules in force.

Speaking in Istanbul on Sunday, Erdoğan had said "Germany! You have nothing to do with democracy. Your recent practices are no different than the Nazi ones of the past," Anadolu Agency reported.

His remarks came in response to German cities' unwillingness to host Turkish politicians attempting to court Germany's sizable Turkish minority on Erdoğan's behalf ahead of a referendum on Turkish constitutional reforms scheduled in April.

A Yes vote in the Turkish referendum would allow Erdoğan to consolidate his authority as both the head of government and head of state, eliminating the role of the prime minister.

Gökay Sofuoğlu, the president of the Turkish community in Germany, also criticized Erdoğan's comments, saying they were "a step too far," NDR reported.

The incident deepens diplomatic tensions between the two countries, which had taken a hit last week over Turkey's detention of a German-Turkish journalist, Deniz Yücel.