More than 200 people have left Germany since 2013 to take up arms with PKK's Syrian offshoot the Democratic Union Party (PYD) and its armed wing, the People's Protection Units (YPG) on the battlefields of Syria and Iraq, 69 of them German passport holders, the German Interior Ministry said in Berlin.
The figure does not include any who might have joined the Peshmerga in northern Iraq. The figures emerged in the German media on Monday following a parliamentary question put by the opposition Left Party.
Of the volunteer terrorists who left since 2013, 102 have since returned to Germany, including 43 German citizens.
Three German citizens are reported to have been killed in the fighting, one of them apparently killed during a Turkish airstrike on a Syrian village.
The German government, which strongly advises against travel to the war regions in Iraq and Syria, said there was no cause to take up the issue with the Turkish government, as the circumstances remained unclear.
Left Party member of parliament Ulla Jelpke expressed criticism of this response.
Turkey considers the YPG a terror group and the Syrian offshoot of the outlawed PKK, which itself is listed as a terror organization by the U.S., Turkey and the EU.
Ankara argues that there is no difference between the YPG and the PKK, as they share the same leadership, ideology and organic organizational links.