Ankara and Berlin are locked in a new dispute weighing on already frayed ties, this time over rallies in Germany by Turkish ministers to promote Erdogan’s bid for greater powers.

The row erupted late last week after three German local authorities banned the ministers’ scheduled rallies ahead of an April referendum over the plan to scrap the prime minister post in Turkey altogether.

The German authorities cited capacity problems in hosting the events, which they said would likely attract large crowds.

Chancellor Angela Merkel has said her government did not have a hand in the decisions, which fell under the jurisdiction of local governments.

But Ankara responded with fury to the cancellations, accusing Berlin of working against the referendum.

Lashing out against Berlin, Erdogan on Sunday told a rally in Istanbul: “Germany, you are not even close to democracy. Your practices are not different from the Nazi practices of the past.”

He also warned Germany not to hinder him from making an appearance if he wished.

“If you don’t let me in, or if you don’t let me speak, I will make the whole world rise up,” he said.

Germany is home to the biggest population of Turkish people abroad, with about three million people of Turkish origin living here, the legacy of a massive “guest worker” programme mainly in the 1960s and 70s.

With some 1.4 million Turks in Germany holding the right to vote in Turkey, it is not uncommon to see politicians travelling there from Ankara to seek to sway the significant voter base.

Undeterred by the numerous cancellations last week, Economy Nihat Zeybekci made a campaign appearance in Cologne on Sunday.

Turkey’s Foreign Minister Mevlut Cavusoglu is also planning to hold a campaign rally on Tuesday in Hamburg.

Altmaier repeated Merkel’s argument that campaign rallies by Turkish ministers, in general, should not be banned.

“But they must adhere to existing rules. They must be registered and subject to checks,” he said.