German political leaders have ruled out the European Union granting Turkey visa-free travel until Ankara fulfills certain requirements.
"There are conditions for visa-free travel and they are known to all sides," Foreign Minister Frank-Walter Steinmeier told the daily Rheinische Post on Tuesday, adding that Turkey "still has work to do."
The visa requirement for Turkish citizens travelling to the EU was originally due to be lifted in July, but the move was stalled because Turkey has not yet fulfilled all 72 criteria for the lifting, among them a reform of a controversial Turkish law on terrorism.
Tensions between Berlin and Ankara intensified this week after Germany's top court, the Constitutional Court, banned Turkish President Recep Tayyip Erdogan from addressing a Sunday rally of his supporters in the western German city of Cologne via a video link.
At the same time, Turkish Foreign Minister Mevlut Cavusoglu threatened in a German newspaper interview to pull out of his nation's refugee deal with the EU unless the Brussels-based bloc agreed to visa-free travel for Turkey's population of 78 million by October.
Germany's vice-Chancellor Sigmar Gabriel hit back saying Germany "should not let itself be blackmailed."
Echoing Gabriel's remarks, Steinmeier said: "It now does not help for each side to make ultimatums and threats."
The European Commission still has faith in the migration deal struck with Turkey, a spokeswoman said Tuesday, stressing that the European Union's executive is not preparing for alternative scenarios.
"We have a Plan A, and that is to make the EU-Turkey deal work," Mina Andreeva told journalists.
Turkey remains a safe third country to return asylum seekers to, she added, referring to "recent commitments made publicly by the Turkish authorities" that the agreement reached between Ankara and Brussels "continues to be effectively implemented."
"The commission has no indication that it's the contrary," Andreeva added.
However, a Socialist EU lawmaker Knut Fleckenstein called Monday upon EU member states to "prepare for the situation that Turkey pulls it support for the refugee deal and be ready with a credible alternative plan."