Turkish President Tayyip Erdogan has crossed a line by comparing Germany's government to the Nazis and is no longer welcome in the country, a major ally of Chancellor Angela Merkel said on Tuesday.

The rebuke from Volker Bouffier, premier of Hesse state, reflected growing exasperation over Erdogan's assertions that Germany and other European powers were using Nazi tactics by banning Turkish political rallies in their territories.

"Enough is enough," said Bouffier, also vice chairman of Merkel's Christian Democratic Union. "Mr. Erdogan and his government are not welcome in our country, and that must be now be understood," he told broadcaster DLF.

Germany media had reported that Erdogan was planning to visit Germany in March to rally Turkish people living there to support a package of new presidential powers in an April referendum.

Bouffier said such a visit would create security problems. "Someone who insults us in this way cannot expect that we will assemble thousands of police to protect him," he said.

Germany's government has said it has not received a formal request for a visit by Erdogan.

Merkel called on Monday for Turkey to stop the Nazi comparisons and said her government reserved the right to block future appearances by Turkish officials if they did not comply with German law.

Reiner Haseloff, another member of Merkel's conservatives and premier of Saxony-Anhalt state, urged Berlin to bar such visits.

"Every statesman that wants to discuss something with us is welcome as a guest, and will be welcomed with the proper diplomatic protocol, but that does not include campaigning, and especially not by people who are discrediting us as a nation," he told the Welt newspaper in an article published on Tuesday.

"Those who compare us to Nazis are not welcome. That is not acceptable," he said, adding that Berlin should not rely on local and state governments to make decisions about visits by Turkish politicians as it has up to now.

Erdogan said in a speech in Istanbul on Sunday: "Merkel, now you're applying Nazi methods. Against my brothers who live in Germany, and against my ministers and lawmakers who visit there."

His Deputy Prime Minister Numan Kurtulmus said a day later that Turkey was using metaphors about "facism" because it was worried about European countries forgetting their history and falling into the trap of Nazism once again.