Turkish President Recep Tayyip Erdogan said Thursday he will keep up his "Nazi" taunts targeting European leaders as long as they keep on calling him a "dictator".

"How does that work, you have the right to call Erdogan a 'dictator' but Erdogan doesn't have the right to call you 'fascist' and 'Nazi'?" he said during an interview with the CNN-Turk and Kanal D television channels.

Relations between Turkey and Europe have been severely strained since Turkish ministers were thwarted from campaigning on the continent for a 'yes' vote in next month's referendum on expanding Erdogan's powers.

Ankara has said such behaviour was reminiscent of Nazi Germany and also raised alarm over what it sees as rising racism and Islamophobia.

Germany on Monday branded as "unacceptable" Erdogan's charge that Chancellor Angela Merkel was using "Nazi measures", but signalled it wanted to avoid escalating the feud.

Erdogan, who has also taken similar aim at the Netherlands, didn't sound conciliatory.

"They accuse me then they speak of Erdogan as a 'dictator," he continued, still referring to himself in the third person.

"So I'll continue to address them in these terms," he added.

'Good friends'

Erdogan again denounced the cancellation of his ministers' trips to European countries with a large Turkish diaspora ahead of the referendum.

On Wednesday he warned that Europeans risk being unsafe on the world's streets, as the crisis between Ankara and the EU showed no signs of abating.

The same day Germany's new President Frank-Walter Steinmeier again urged the Turkish leader to "stop these appalling comparisons with Nazism, do not cut the ties with those who want a partnership with Turkey."

Erdogan said he was "good friends" with Steinmeier and "deplored" his comments.

He added that there could be a "period of review" of Turkey relations with the European Union, while stressing the importance of economic ties with the bloc, his country's biggest trading partner.

Turkey is officially an EU-candidate nation but its accession process has been practically blocked for years.

He said that an EU-Turkey agreement on migrants, aimed at reducing the numbers reaching Europe from Africa and the Middle East, would be part of an "A to Z" review of government policy to begin after the April 16 referendum.

'Saddened'

Turning to the issue of Kurdish separatists in Turkey and Syria, the Erdogan said he was "saddened" by links which Russia and the US have with Kurdish militias.

While he is a regular critic of Washington over its support for the Kurdish YPG militia operating in Syria it was the first time he had expressed his unhappiness with Moscow's stance

Turkey summoned the Russian charge d'affaires on Wednesday and sent him another message Thursday to convey "deep unease" over two incidents in Kurdish militia-controlled Syria, Ankara said.

Ankara said one of its soldiers had been shot and killed in southern Turkey on Wednesday by cross-border sniper fire from an area of northwestern Syria controlled by the Kurdish YPG militia.

On Thursday, the foreign ministry sent a new message to the Russian envoy over photos of Russian troops apparently showing them wearing YPG insignia, state-run news agency Anadolu said.

The YPG confirmed on Monday that they had received military training from Russian operatives, something Moscow has not confirmed.