(CNN)Turkish President Recep Tayyip Erdogan has accused German Chancellor Angela Merkel and her election rival Martin Schulz of "bowing down to populism and prejudice" after both candidates called for an end to Ankara's European Union membership talks in a live TV election debate Sunday night.
Turkey accuses German politicians of 'bowing down to populism'
In a series of tweets posted Monday morning, presidential spokesperson Ibrahim Kalin said that the two candidates chose to attack Turkey and Erdogan "while ignoring Germany and Europe's fundamental and critical issues" and accused Germany of embracing the Kurdistan Workers Party, or PKK, a Kurdish separatist group that the Turkish government has branded a terrorist organization.
Turkey's deputy Prime Minister, Mehmet Sismek, also reacted on Twitter. "EU never had a credible commitment to let Turkey in," he wrote Monday. "Merkel isn't only shooting herself in the foot but also jeopardising the future of Europe."
In the debate Sunday night -- three weeks before Germany's federal election -- Merkel called for accession negotiations to be stopped in an apparent change of stance on Turkey's bid to join the EU.
"Turkey should not be a member of the EU," Merkel said. "I will discuss with colleagues again to see if we can come to a joint position and end these accession negotiations."
But she insisted that it was important for the two countries to keep talking, especially in light of the Germans currently being held as political prisoners in Turkey.
"I have no intention of ending diplomatic relations with Turkey," Merkel said.
More than 10 Germans are being held. Two were arrested Friday, according to German authorities, but one has since been released, according to CNN affiliate N-TV.
Her Social Democratic rival also said he would seek to end membership talks. "We would be accepting someone who is now visibly calling into question all of the basic values of European cooperation," Schulz said.
Turkey has "overstepped all red lines."
The exchange of blows marks a further escalation in tensions between the two countries.
Relations between Berlin and Ankara have been in a downward spiral since last summer, when a failed coup against Erdogan sparked a crackdown on civil liberties and mass arrests of the political opposition, activists and journalists, including German citizens.
Speaking at her annual summer news conference last week, Merkel said Turkey's jailing of Germans was further damaging already fraught ties between the two countries, saying their imprisonment was "unjustified."
Among the prisoners is German-Turkish journalist Deniz Yucel, who was arrested in Turkey in February on charges of terror propaganda, and human-rights activist Peter Steudtner, held since July with nine others and charged with "committing crimes in the name of a terrorist organization without being a member."
Germany has changed its tactics over Turkey in recent months, threatening to impose travel and trade restrictions if journalist Yucel and activist Steudtner aren't released from prison.
In July, German Foreign Minister Sigmar Gabriel warned Germans against traveling to Turkey and suggested that the German government would review corporate investments in Turkey.
"Someone who detains law-abiding visitors to their country on the basis of outlandish, indeed absurd, accusations and throws them into prison has left European values behind," Gabriel said, calling for Steudtner's release. "We cannot continue as before."
A few weeks earlier, Turkey's Foreign Ministry criticized an art installation in Berlin depicting Erdogan as a dictator that coincided with the G20 summit in Hamburg, calling it "a new example of rising racism and xenophobia in the country."
Soon after, the Turkish government blocked German lawmakers from visiting German troops stationed in Turkey participating in NATO operations in Syria.
Earlier this year, German officials prevented top politicians, including Erdogan, from addressing Turkish rallies in Germany in the lead-up to an April referendum that handed Erdogan sweeping new powers.
In response, Erdogan likened the German government to that of Adolf Hitler. "I thought that Nazism was over in Germany, but it turns out that it is still going on," he said. "It is still going on, it is clear."
Relations with Turkey are a key issue in the days leading to federal elections in Germany, where there are some 3 million people with Turkish roots.
Earlier this month, Erdogan called on voters of Turkish origin to boycott the two biggest parties -- Merkel's Christian Democrats and the Social Democrats -- along with the Green Party in the election, describing them as "enemies of Turkey," according to CNN affiliate NTV.
The call drew a fierce rebuke at the time from Merkel, who warned Erdogan against interfering in the election.
Germans go the polls September 24, with Merkel widely expected to secure a fourth term.