German-Turkish author Dogan Akhanli was arrested in Spain on Saturday after Turkey issued an Interpol warrant for the writer, a critic of President Recep Tayyip Erdogan's government, fanning an already fierce row between the North Atlantic Treaty Organisation allies.
"That's not on. We must not misuse global organisations such as Interpol" in such cases, she said on RTL television about the case of writer Dogan Akhanli, who was arrested Saturday at Turkey's request while holidaying in Spain.
The arrest shows that Erdogan is seeking to "extend his power beyond his country's borders, to intimidate critics and to pursue them around the world", Beck said.
Germany's Gabriel welcomed the release from detention of writer Dogan Akhanli, who must remain in Spain while Spanish authorities assess Turkey's extradition request.
German Foreign Minister Sigmar Gabriel also greeted the writer's release and said "it would be awful if, even on the other side of Europe, Turkey succeeded in having people who raise their voices against President Erdogan arrested".
"That is why we massively changed out Turkey policy", Merkel said, speaking at a "town hall meeting" forum with voters, referring to stepped up travel warnings for German tourists and moves likely to dampen new investment in Turkey.
The already high tensions between the two countries hit another peak on Friday when Erdoğan said all of Germany's mainstream parties were enemies of Turkey and urged Turkish-Germans to not vote for them in the upcoming election.
Turkish accusations include the charge that Germany has given refuge to wanted Kurdistan Workers' Party (PKK) militants and suspected coup plotters.
Gabriel, a senior member of the SPD, had bitterly denounced Erdogan's remarks as an "unprecedented act of interference" in Germany's sovereignty.
Merkel called Erdoğan's comments "completely unacceptable". Talk to Turkey's foreign minister. He fled to Germany in 1991 as a refugee, achieving citizenship in 2001.
Akhanli has written about the killing of Turkish-Armenian journalist Hrant Dink, who was murdered in 2007, and about the killing of Armenians under the Ottoman Turkish empire.
German Green MPs have long taken up the cause of Akhanli, saying he is a victim of political persecution.
Between half a million and 1.5 million Armenians were killed between 1915 and 1917, a bloodletting that Armenia and Western historians describe as genocide.
Akhanli was arrested in 2010 on his arrival in Istanbul airport for alleged implication in an armed robbery in 1989. He was acquitted and released after a number of months - only to have proceedings reinstated at a later date.