BERLIN (Reuters) - German Foreign Minister Frank-Walter Steinmeier criticized Turkey’s arrest of Kurdish opposition leaders on Friday, saying Ankara had a right to fight terrorism but could not use it to justify gagging opponents.

Demonstrators scuffle with riot police during a protest against the arrest of pro-Kurdish Peoples' Democratic Party (HDP) lawmakers, in Ankara, Turkey, November 4, 2016. REUTERS/Umit Bektas

Steinmeier summoned Ufuk Gezer, the Turkish charge d’affaires, to discuss the arrest of nearly a dozen leaders and lawmakers from the Kurdish Peoples’ Democratic Party (HDP), the second-biggest opposition group in the Turkish parliament.

Austria’s Foreign Ministry also summoned Turkey’s top diplomat in Vienna to express dismay about the arrests.

“The fight against terrorism cannot be used as a justification for silencing the political opposition or even putting them behind bars,” Steinmeier told reporters after a meeting with British Foreign Secretary Boris Johnson.

Steinmeier condemned a car bomb attack that rocked Diyarbakir, southeastern Turkey’s largest city, on Friday, killing at least one person and wounding more than 100.

The German minister said he supported Turkey’s aspiration to join the European Union, but Ankara needed to be clear about what its actions meant for its relationship with the EU.

Horst Seehofer, state premier of Bavaria and leader of the CSU sister party to Chancellor Angela Merkel’s Christian Democrats (CDU), said the EU should suspend accession talks with Turkey and drop any plans to offer visa-free travel to Turks.

Those are key conditions of a deal, vital to Merkel, under which has Turkey has dramatically reduced the number of migrants crossing to EU member state Greece from its shores in recent months.

Johnson told reporters that Turkey was a key partner in the joint fight against Syrian ruler Bashar al-Assad, but Britain and Germany had serious concerns about Ankara’s handling of the media and political parties.

Tensions have been building between Germany and Turkey on a range of issues.

Turkish President Tayyip Erdogan on Thursday said Germany had become a haven for terrorists and accused it of failing to root out supporters of a U.S.-based cleric Ankara blames for July’s failed military coup.

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Erdogan said Germany had long harbored militants from the Kurdistan Workers Party (PKK), which has waged a three-decade insurgency for Kurdish autonomy, and far-leftists of the DHKP-C, which has carried out armed attacks in Turkey.

“GESTAPO TACTICS”

Steinmeier and other European officials have raised concerns about Turkey’s detention or suspension of more than 110,000 officials in the wake of the failed putsch.

German government spokesman Steffen Seibert said the latest arrests confirmed concerns first raised in May, when the Turkish parliament stripped members of their immunity from prosecution.

Can Dundar, the former editor of the Turkish opposition daily Cumhuriyet who now lives in Berlin, said Erdogan’s government was using “Gestapo tactics” to silence his critics.

“Without a parliament, without the rule of law, without a free press, what do you think is left in the country? Just the fascists,” he told Reuters Television.

“He’s just trying to get rid of all kinds of critical voices.”

EU foreign policy chief Federica Mogherini said on Twitter she was “extremely worried” by the arrests and had called a meeting of EU ambassadors in Ankara.

Maria Boehmer, a state secretary in the German Foreign Ministry, had been due to meet in Ankara on Friday with Figen Yuksekdag, one of the HDP leaders who was arrested.

Boehmer said she had expressed her concerns about Turkey’s escalating domestic political situation during talks with the Turkish youth minister and the deputy foreign minister.

“Protecting the rights of lawmakers is a decisive characteristic of functioning democracies,” she said in a statement released by the ministry.

She offered Germany’s support to Turkey in its fight against militant groups, but said the German government expected Turkey to find a political solution to its issues with the Kurds.

Ali Etran Toprak, head of Germany’s large Kurdish community, called on Berlin and its EU partners on Friday to stop cooperating with the Turkish government on refugees and halt EU membership talks with Ankara following the arrests.