In a heated row over banned Turkish government rallies on European soil, President Recep Tayyip Erdogan showed no signs of backing down on Sunday, this time directing accusations of Nazi behaviour at German Chancellor Angela Merkel herself.
Erdogan had previously accused the German and Dutch governments of engaging in "Nazi practices" after both countries prevented Turkish ministers from campaigning at events for expatriate voters ahead of an upcoming referendum.
"You are currently employing Nazi methods," he said in Istanbul, taking aim at the German chancellor.
"Against whom? Against my Turkish brothers and sisters in Germany, against my minister brothers and sisters, against parliamentary brothers and sisters who travel there."
Erdogan and his surrogates are currently trying to court the millions of Turks living in Germany and elsewhere in Europe ahead of a referendum in April on the expansion of the president's powers.
But German authorities have cancelled several planned rallies in recent weeks.
Lashing out at Europe, Erdogan said "gas chambers and concentration camps" could once again be on the table, but that "they don't have the nerve for that." It was unclear to whom exactly he was referring.
German-Turkish relations were already under strain because of Turkey's jailing of a reporter for Germany's Die Welt newspaper. Denis Yucel was taken into pre-trial detention late last month. It could take five years until he is released or faces trial.
Yucel faces terrorism-related charges in Turkey. He had previously reported on the government's use of trolls on social media in a scandal involving Erdogan's son-in-law, Energy Minister Berat Albayrak.
Turkey has meanwhile accused Germany of siding with terrorists following an attempted coup on July 15. Ankara believes cleric Fethullah Gulen was behind the plot.
However, German intelligence agency chief Bruno Kahl told German news magazine Der Spiegel that Turkey "has not succeeded" in backing up this claim.
Incensed by the intelligence chief's scepticism, Turkish Defence Minister Fikri Isik wondered "whether the German intelligence service might not be behind the putsch," in comments to broadcaster Kanal 7 on Sunday. He offered no evidence to support the claim.