Turkey on Tuesday, March 21 scrapped all future campaign appearances by its politicians in Germany ahead of April's referendum on expanding President Recep Tayyip Erdogan's powers, amid a heated diplomatic row, AFP reports.

The sudden decision came after three weeks of furious exchanges between Turkey and the European Union over the pro-Erdogan rallies which were banned in some of the bloc's member states.

"All future events that were planned have been cancelled. That is a decision that was made in Ankara," said a Cologne-based spokeswoman for Erdogan's AKP party.

Turkish ministers eager to tap into 1.4 million voters in Germany have sought to campaign in Europe's most populous country to whip up support for a "yes" vote in the April 16 referendum on scrapping the prime minister's post and creating a executive presidency.

However, several were recently rebuffed when German local and state authorities blocked the rallies, citing logistical reasons.

After explicitly saying such campaign appearances were not welcome, The Netherlands simply refused to allow Foreign Minister Mevlut Cavusoglu's plane landing rights and expelled another envoy who had travelled in by road.

Ankara reacted with fury, with Erdogan accusing Germany and The Netherlands of "Nazi" practices, sparking uproar in Europe.

On Monday, Chancellor Angela Merkel warned that Germany could issue a blanket ban against future campaign events by Turkish politicians unless Ankara halted its Nazi insults.

Such comments were "breaking every taboo, without consideration for the suffering of those who were persecuted and murdered" by the Nazis, she said.

Rotterdam mayor Ahmed Aboutaleb separately appealed for calm Tuesday among the Dutch city's sizeable Turkish community, after an unauthorised pro-Turkey demonstration in the port city flared into violence 10 days ago.