Turkish President Recep Tayyip Erdogan's sweeping crackdown in the wake of last week's failed military coup has intensified the tensions surrounding the recently fraught relations between Berlin and Ankara.
Berlin warned Erdogan on Monday not to reintroduce the death penalty to deal with the coup plotters and expressed worries about Turkey's "cleanse" amid deepening concerns in Germany about a period of turmoil as Ankara seeks to reassert its authority in the country.
Ankara's response must be "based on the rule of law", said German Chancellor Angela Merkel's spokesman, Steffen Seibert, who said that moves by Erdogan to reintroduce the death penalty to deal with the coup plotters would end Turkey's hopes of joining the European Union.
He went on to express concern about the number of judges who have been removed from their posts since the coup and the "repulsive scenes" of retribution against rebel soldiers. "That cannot be accepted," said Seibert.
The attempted coup came against the backdrop of months of frictions between Ankara and Berlin culminating in the German Parliament declaring in June that the killings a century ago of as many as 1.5 million Armenians at the hands of the Ottoman Empire was genocide.
The parliament's resolution infuriated Ankara. Turkey, the Ottoman Empire's successor state, responded to the resolution by recalling its ambassador to Germany for consultations.
At the same time, Erdogan lashed out at Berlin, warning about the impact on relations between the two nations and attacking Merkel for failing to head off the parliamentary vote.
Since then, the two sides have been locked in a stand-off over German lawmakers visiting about 270 German troops stationed at the Turkish airbase Incirlik as part of the international fight against the extremist militia Islamic State. Ankara blocked political delegations from travelling to the base following the vote on Armenia.
The tensions unleashed by the Armenia resolution came after Merkel spearheaded a difficult round of negotiations with Turkey for a deal whereby Brussels promised to pay Ankara 6 billion euros (6.6 billion dollars) over the next three years.
Seibert insisted that the upheaval under way in Turkey did not pose a threat to the refugee agreement, which has helped to halt the stream of refugees making the often hazardous journey across the Aegean Sea from Turkey to the EU via Greece.
However, talks are making slow progress on another even more complicated part of the deal, which is to grant Turks visa-free travel to the EU's open-border Schengen area of 26 nations.
The EU has laid out a series of benchmarks that Turkey must introduce before visa-free travel can be agreed to.
But EU leaders are also facing a political backlash over migration, which is likely to act as a hurdle to an early agreement on Erdogan's hopes of visa-free travel for Turks.
Since the coup attempt, thousands of the almost 3 million people living in Germany with a Turkish background turned up at Ankara's diplomatic offices across Germany to show their support for Erdogan.
But the Turkish population in Germany is also deeply divided and includes supporters of the banned Kurdistan Workers' Party as well as critics of Erdogan and his government.
Gokay Sofuoglu from the Turkish Community in Germany condemned the coup, but added, "I am watching developments with great concern."
Germany is Turkey's biggest trading partner, with German business seeing Turkey as a door to neighbouring regions such the Middle East.
German exports have also jumped in recent years, climbing 16 per cent in 2015 to 22.4 billion euros (24.8 billion dollars) compared with 2014.
There are now 6,500 companies in Turkey which are either German owned or backed by German investors. This includes some of Germany's biggest companies, like engineering giant Siemens and retailer Metro. Turkey is also a major destination for German tourists.
The Turkish economy has, however, been reeling from a string of recent deadly terrorist attacks with the coup and the risks of political instability adding to worries about the nation's business outlook.
"The events in Turkey increase the sense of uncertainty, including with companies," the president of the German Chamber of Commerce (DIHK), Eric Schweitzer, said in Berlin on Monday.
In depth coverage
Turkish authorities, including prosecutors, on Monday began a search at Incirlik airbase in the south of the country, Hurriyet newspaper reported, as the retribution against this weekend's coup-plotters in Turkey picked up pace.
Turkey's reintroduction of the death penalty would end its European Union membership talks but did not place at risk the EU's refugee deal with Ankara, German government spokesmen said on Monday.
A country that has the death penalty cannot join the European Union, the bloc's foreign policy chief says in a warning to Turkey.
Turkey's Interior Ministry says 8,777 people have been removed from their posts, including 7,899 members of the police and security forces, the state-run Anadolu news agency reports.