Turkish President Recep Tayyip Erdogan on Friday pledged to keep up his tough rhetoric on Europe, despite calls from EU leaders, including German Chancellor Angela Merkel, to tone down the insults.

"As long as you call Tayyip Erdogan dictator, know that Tayyip Erdogan will call you both fascist and Nazi," Erdogan said at a campaign rally in Denizli in the south-west.

Tensions have grown between Europe and Turkey after Germany and the Netherlands banned rallies in their countries by Turkish government ministers looking to win expatriate votes ahead of an April 16 referendum that would expand Erdogan's presidential powers.

Erdogan said that the bans amounted to "Nazi practices."

"My statement that the Nazi comparisons from the Turkish side have to stop applies without ifs or buts," Merkel said this week.

At the rally, Erdogan repeated his desire to bring back the death penalty. EU officials have said that legalizing capital punishment again would spell the end of Turkey's bid to join the bloc.

Erdogan expressed anger at Germany's intelligence chief having cast doubt on Ankara's version of events regarding last year's failed coup attempt, which the Turkish government blames on US-based cleric Fethullah Gulen.

"Know your place," Erdogan said, while also telling the crowd not to trust Westerners.

The Turkish president this week upset Europeans by implying that their safety was at risk unless the EU changes its approach to Turkey.

The Turkish ambassador was this week summoned to Brussels to explain the comments.