By Thomas Escritt and Shadia Nasralla
ROTTERDAM/VIENNA (Reuters) - Turkish Foreign Minister Mevlut Cavusoglu will not be allowed to campaign for votes among expat Turks during a visit to Rotterdam on Saturday, the mayor of the Dutch port said, joining a growing list of European cities that have blocked such rallies.
"He has diplomatic immunity and everything so we will treat him with respect, but we have other instruments to prohibit things happening in public spaces," Mayor Ahmed Aboutaleb told reporters.
Four planned Turkish political meetings in Austria and one in Switzerland were also canceled, in the latest signs of unease across Europe over Turkey's efforts to rally support for President Tayyip Erdogan in the run-up to an April 16 referendum on granting him extensive new powers.
Relations between Turkey and the European Union have deteriorated in recent months, with Erdogan bristling at criticism from EU members for waging a mass crackdown on opponents since he saw off a coup attempt last July.
The row over campaigning among the large Turkish communities in Europe has exacerbated tensions. Erdogan has compared the cancellation of rallies in Germany with Nazi-era fascist tactics; Chancellor Angela Merkel said on Thursday that such comments were 'unworthy' and must stop.
Having survived the July coup, Erdogan says the referendum is needed to guarantee stability. European politicians accuse him of using the failed putsch as a pretext for mass arrests and dismissals that stifle dissent.
The proposed constitutional changes to greatly strengthen his powers would be a "dangerous step backwards" for democracy, a panel of legal experts at the Council of Europe said on Friday.
It said the amendments would give the president "the power to dissolve parliament on any grounds whatsoever, which is fundamentally alien to democratic presidential systems".
The legal opinion has no binding power over Turkey, which joined the 47-nation Council of Europe in 1950.
Swiss police cited "significant security risks" for their decision to cancel a speech by a Turkish politician on Friday evening.
Foreign Minister Cavusoglu is still looking for a new venue for an event on Sunday after one hotel near Zurich pulled out on security grounds and an alternative, in the city of Winterthur, was rejected as inappropriate.
A call by Zurich's security chief for Cavusoglu to be barred from speaking there has been rejected by the Swiss government.
The Austrian town of Hoerbranz canceled an event with a former Turkish minister because the organizers had falsely labeled it as a book presentation. Other events were scrapped in Linz, Herzogenburg and Wiener Neustadt.
Austria's interior minister said on Tuesday he wanted to change the law to permit a ban on foreign officials making speeches in the country if human rights or public order are threatened, but the bill has not reached parliament yet.
(Additional reporting by John Miller in Zurich and Julia Fioretti in Brussels; Editing by Mark Trevelyan)