ANGELA Merkel has said her demand for Turkey to cease drawing Nazi comparisons with Germany and its allies applies "without ifs or buts".
The German chancellor also pointed to a government threat last week that it could prevent Turkish politicians from entering the country.
Mrs Merkel's comments came after Turkish president Recep Tayyip Erdogan accused her personally of "committing Nazi practices".
The accusation on Sunday was the latest in a string of comments by Turkish officials drawing Nazi parallels with present-day Germany and the Netherlands in a dispute over restrictions on Turkish ministers campaigning there for an upcoming referendum.
Some local German authorities have decided to block appearances by Turkish ministers ahead of the vote next month, but Mrs Merkel's federal government - unlike its Dutch counterpart - has made no such decisions so far.
Her chief of staff, though, did say last week that it reserves the right to impose entry bans as a "last resort".
Mrs Merkel said at a joint press conference with visiting Japanese prime minister Shinzo Abe in Hannover: "My comment that the Nazi comparisons on Turkey's part must end is valid without ifs or buts.
"Unfortunately, we see that these comparisons have not ceased, and we are not going to allow ... every taboo to be broken with no regard to the suffering of those who were persecuted and murdered under Nazism."
Mrs Merkel pointed to a foreign ministry note sent to Turkey last week allowing Turkish referendum polling stations in Germany, in which Ankara was told that appearances by Turkish politicians must respect the principles of the German constitution, and that Berlin otherwise reserves the right to "take all necessary measures".
Mrs Merkel's pointed but guarded response was in line with German officials' statements over the past week that she has "no intention of participating in the race of provocations".
Peter Tauber, the general secretary of Mrs Merkel's conservative party, told N24 television that "this is real effrontery toward our chancellor".
However, he added that "we can allow ourselves to be outraged, stamp our feet and perhaps fight back - but the chancellor has to safeguard our country's interests".
The European Parliament's president, Antonio Tajani, wrote on Twitter: "An unacceptable attack by RT-Erdogan on a democratic country that guarantees all fundamental rights."
