The German government says that it wouldn't allow voting in Germany in any possible referendum on whether to reintroduce the death penalty in Turkey.
Turkish President Recep Tayyip Erdogan has spoken of reinstating the death penalty - a move that would effectively finish off Ankara's faltering bid to join the European Union - since narrowly winning expanded powers last month. Germany and other European countries vehemently oppose executions.
The German government says that its permission is required for voting in foreign elections or referendums to take place at embassies, consulates or elsewhere on its territory. It permitted polling stations for Turkish nationals in last month's Turkish constitutional referendum.
Germany has a large ethnic Turkish minority and about 1.4 million people living in Germany are eligible to vote in Turkish elections and referendums.
However, Chancellor Angela Merkel's spokesman, Steffen Seibert, said that "there is no obligation" for the German government to approve a request from a foreign country.
"It is politically inconceivable that we would agree to such a vote in Germany on a measure that clearly contradicts our constitution and European values," Seibert told reporters in Berlin. "I assume that we would use all legal means to prevent something like this."
In comments published earlier Friday, Merkel's challenger in Germany's Sept 24 election took a similar line.
"If the Turkish government really held a referendum on the introduction of the death penalty, it must be clear that such a vote must not take place among Turks living in Germany," Martin Schulz told the weekly Der Spiegel. "We cannot allow voting in Germany on an instrument that contradicts our values and our constitution."
Schulz's center-left party is the junior partner in Merkel's current coalition government.
Tensions between Turkey and Germany soared ahead of last month's constitutional referendum.
Erdogan accused Germany, and Merkel, of "committing Nazi practices" after some local authorities blocked appearances by Turkish ministers hoping to campaign in Germany.