ANKARA/BERLIN (Reuters) - Germany said on Friday it was reviewing applications for arms projects from Turkey, accusing its NATO ally of ramping up covert operations as an attempt by a Turkish minister to calm a deepening bilateral crisis fell flat.
While one minister in Berlin compared Ankara's behaviour over the detention of six rights activists to the authoritarian former communist East Germany, Turkish President Tayyip Erdogan told Germany to "pull itself together".
Bilateral tensions were already high after bitter recriminations during a referendum in April on extending Erdogan's powers and a pullout of German troops from a Turkish air base that began this month.
They rose further after Turkey detained the activists, including a German national, in custody two weeks ago.
Turkey's economy minister sought to calm matters but Erdogan, renewing earlier criticism, accused Berlin of trying to scare German companies away from investing in Turkey.
Germany, home to three million people with Turkish roots, said it would review Turkish applications for arms projects. "We're checking all applications," an Economy Ministry spokeswoman said.
That means the Federal Office of Economics and Export Control (Bafa) probably cannot issue new export approvals, but projects already agreed will not be affected initially.
In 2016, the German government exported armaments worth 83.9 million euros to Turkey. In the first four months of 2017, business worth 22 million euros was approved, for navy deliveries and joint projects with other NATO partners.
Germany has warned Germans travelling to Turkey that they do so at their own risk, and Finance Minister Wolfgang Schaeuble was quoted on Friday as comparing Turkey with the former communist East German state - the German Democratic Republic (GDR).
"Turkey now makes arbitrary arrests and no longer sticks to minimum consular standards. That reminds me of how it was in the GDR," he told the mass-circulation Bild newspaper.
Schaeuble said those who travelled to the former Communist East before it collapsed in 1990 were aware that "if something happens to you, no one can help you".
German officials say they have not had full consular access to arrested German activist Peter Steudtner, who was accused of terrorism - an allegation Berlin has dismissed as absurd. Another German citizen was arrested on charges of links to terrorism earlier this year.
Germany's domestic security chief said Turkey had been carrying out ever more covert operations in Germany, especially since a failed coup attempt against Erdogan last July.
"Since the coup attempt and domestic political changes there, we no longer see Turkey's intelligence service purely as a partner but also as an opponent," BfV chief Hans-Georg Maassen said.
Covert activities included influence operations targeting Germany-based Turks, with attempts to intimidate opponents of Erdogan.
In March, German authorities barred Turkish ministers from speaking at mass rallies of expatriates backing the president's referendum campaign. He responded by accusing Berlin of "fascist actions".
The activist arrests were part of a broader crackdown across Turkish society since last year's failed coup. More than 150,000 people have been sacked or suspended from jobs in Turkey's civil service, military and private sector and more than 50,000 have been jailed.
Rights groups and some Western governments say Erdogan is using the crackdown as a pretext to quash dissent. The Turkish government says the measures are necessary given the gravity of the security threat it faces.
They may have extended to German companies.
A security source told Reuters Turkey had sent German authorities a list of over 680 firms it suspected of supporting terrorism.
Turkey's Economy Minister Nihat Zeybekci told Reuters Germany's behaviour in cautioning its citizens over travel to Turkey was "unfortunate", but he did not see harm accruing to tourism.
So far this year, bookings from Germany have accounted for some 10 percent of Turkey's tourists.
Last year, the number of foreign visitors to Turkey fell 30 percent amid bombings by Kurdish and Islamist militants, the lowest in nine years. The travel sector contributes about $30 billion to the economy in a normal year.
Commercial links are close.
Germany was Turkey's top export destination in 2016, buying $14 billion worth of Turkish goods, and the second biggest source of Turkish imports, at $21.5 billion.
German news broadcaster n-tv said it would no longer run adverts that aimed to attract investment in Turkey.
Additional reporting by Thorsten Severin and Thomas Escritt in Berlin and Ece Toksabay and Tuvan Gumrukcu in Ankara; Writing by Paul Carrel; Editing by Ralph Boulton and John Stonestreet