Turkey on Monday accused German politicians of surrendering to populism and urged them to give up their “careless language” after Chancellor Angela Merkel said she would seek to end talks on Ankara's accession to the European Union.

Relations have been strained between Ankara and Berlin since the crackdown that followed last year's failed coup in Turkey that has seen more than 50,000 people arrested.

Turkish European Union Affairs Minister Omer Celik said discussion over “ending negotiations with Turkey is an attack on the EU's founding values”.

In a TV showdown with challenger Martin Schulz on Sunday ahead of a September election, Merkel said it was “clear that Turkey should not become a member of the European Union”.

Merkel said she would discuss with EU counterparts if “we can end these membership talks”, adding: “I don't see (Turkey) ever joining and I had never believed that it would happen.”

Her strong stance against Turkey appeared to steal the show from Schulz, who had minutes earlier called for an end to the EU membership talks.

Celik hit back at German politicians using “careless language” and “trying to give orders to EU institutions... they think the EU is the 'United States of Germany'”.

He added the attitude of some German politicians was to “build a Berlin Wall with bricks of populism”, heavily criticising Schulz but only directly accusing Merkel of taking a position against Turkey to “avoid falling behind”.

The Turkish foreign ministry accused German politicians of encouraging Islamophobia, adding that Turkey had helped Europe during “large chaos” when refugees fled to the continent during the 2015 migrant crisis.

'Populism fuels racism'

Turkish Foreign Minister Mevlut Cavusoglu said Europe “was turning to the values of the pre-Second World War era... savagery, fascism, violence, intolerance”.

Earlier, President Recep Tayyip Erdogan's spokesman said attacks on Turkey were a “surrender to populism and marginalisation [and] hostility [which] only fuels discrimination and racism”.

“Attacking Turkey-Erdogan and ignoring Germany's and Europe's fundamental and urgent problems are a reflection of a lack of vision,” Ibrahim Kalin said on Twitter.

Bilateral ties between the Nato allies worsened after Turkey detained German citizens including Turkish-German journalist Deniz Yucel, the Istanbul correspondent for the Die Welt newspaper.

Yucel has now spent over 200 days in custody ahead of a trial on terror charges.

Last week two more German citizens of Turkish origin were arrested, but the German foreign ministry Monday said one of them had been freed without restrictions, according to her lawyer.

She is expected to arrive in Germany in the next few days.

The ministry said it was still seeking independent confirmation of the release, but it brings the total number of Germans in Turkish custody down to 11.

EU foreign policy chief Federica Mogherini said Turkey remained a partner in the region and was still a candidate country.

“So, we will continue talks, it will be up to the internal discussions we will have and most of all to the discussions we will have together with them to define the future of our relations,” she said at the end of an economic forum on Monday.

'Is Germany defending terrorists?'

Erdogan has previously accused Germany of sheltering coup plotters as well as Kurdish militants and demanded their extradition.

Erdogan's spokesman appeared to suggest that Germany supported terrorism, by giving space to groups like the Kurdistan Workers' Party (PKK) and the movement led by US-based Islamic cleric Fethullah Gulen who is accused of ordering the July 15, 2016 attempted putsch.

Gulen strongly denies the charges but Turkey calls his movement the “Fethullah Terrorist Organisation” (FETO). The movement denies this, insisting it promotes Islam, charity and education.

“Is Germany, which openly embraces organisations like the PKK and FETO, not aware that it defends terrorists and coup-plotters, not democracy?”

Last month, Erdogan urged ethnic Turks in Germany to vote against Merkel's conservatives and their coalition partners, the Social Democrats, in the election.

But Kalin dismissed the vote, saying: “It does not matter which party wins in the German elections because the mentality which will win is now obvious.”

The escalating tensions have split the Turkish community in Europe's top economy, the largest Turkish diaspora abroad, which is a legacy of Germany's “guest worker” programme of the 1960s and 70s.