Brussels: The European Union's top officials sharply criticised Turkey on Wednesday for accusing EU states Germany and the Netherlands of fascism, saying the charges were driving Ankara further away from its goal of joining the bloc.

A war of words between Turkey and the EU has erupted this month over planned rallies by Turkish politicians in Rotterdam and other European cities that aimed to drum up support for plans to give Turkish President Tayyip Erdogan sweeping new powers.

The Netherlands cancelled the Rotterdam rally, prompting Erdogan to brand the country as "Nazi remnants". He has also accused Germany, which has also cancelled several planned Turkish rallies, of "fascist actions" reminiscent of the Nazi era and has said "Nazism is still widespread in the West".

"Rotterdam, the city of Erasmus, totally destroyed by the Nazis, which now has a mayor born in Morocco: If any anyone sees fascism in Rotterdam they are completely detached from reality," European Council President Donald Tusk told a plenary session of the European Parliament, speaking in English and Dutch.

Tusk's remarks were echoed by European Commission President Jean Claude Juncker, who told parliament he was "scandalised" by the Turkish accusations about fascism and Nazism.

"If you are establishing a comparison between that period and our times this is totally unacceptable and the one who is doing this is taking distance from Europe and not trying to enter the European Union," Juncker said.

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Erdogan, who survived a military coup last summer, has defended his plans to amass greater powers in a referendum set for April 16, saying Turkey needs greater stability. But his crackdown on dissenting voices among the judiciary and the media since the failed coup has drawn strong criticism in the West.

But the EU is caught between holding Erdogan accountable and guaranteeing the continuation of a deal to control the flow of refugees and migrants who pass through Turkey to Europe.

This deal has given the EU a badly-needed breathing space after more than a million people, mostly fleeing conflicts in Syria and elsewhere in the Middle East, fled to the bloc in 2015-16 via Turkey, Greece and the Balkans.

Turkey's EU affairs minister, Omer Celik, told Reuters on Tuesday it was time for Ankara to reassess that deal as the EU had failed to deliver on its promise to provide visa-free access to Europe.

EU officials, however, have said they are not yet worried that the deal could collapse.

"Erdogan knows he cannot blow it up ... he needs our money. He is nervous because he may lose his referendum," a senior EU diplomat said.