Foreign Minister Mevlüt Çavuşoğlu warned Germany about "crossing the line" ahead of general elections in the country, shortly after his German counterpart Sigmar Gabriel told a news outlet that Turkey will never be a member of the European Union as long as President Recep Tayyip Erdoğan stays in power.

"Germany must be careful about how it conducts foreign policy with Turkey" Çavuşoğlu said in Poland and added that a populist approach is not the answer to solve ongoing problems between the two countries.

Relations between Turkey and Germany, home to 3 million ethnic Turks, have been badly strained, particularly since the failed coup attempt a year ago against Turkey's democratically elected government by the Gülenist Terror Group (FETÖ). Turkey accuses Germany of harboring high-ranking FETÖ figures and soldiers linked to the coup attempt, in addition to activities of PKK and DHKP-C terrorist groups in Germany.

The two countries were also involved in a bitter diplomatic spat over German parliament's bill describing 1915 events as "genocide" and Turkey's counter measure of preventing German lawmakers to visit German anti-Daesh troops deployed at the Incirlik base. Germany pulled out its 260 military personnel and fighters from Turkey in June, and redeployed them in Jordan.

The spat has also cast clouds over a 2016 deal between Ankara and the EU that has stemmed the mass influx of migrants and refugees into the block.