German authorities banned two media organizations it said were linked to the outlawed Kurdistan Workers' Party (PKK) following raids on Tuesday.
Police searched the Mesopotamia Publishing House and MIR Multimedia in the western states of North Rhine-Westphalia and Lower Saxony and seized material, the Interior Ministry said.
PKK is considered to be a terrorist organisation by the European Union and Turkey.
Read more: Kurds in Germany: Fear is in the air
The ministry said the groups were posing as publishing companies, but the earnings from the two organizations went exclusively to the PKK and strengthened its capabilities in Germany.
"As the PKK is still active despite being banned in Germany, it is necessary to rein in the PKK and uphold our legal system," Interior Minister Horst Seehofer said.
With about 14,500 supporters, the PKK is the biggest radical foreign organization in Germany, which is a base for recruitment and refinancing.
Relations between Germany, where there are some 3 million people with a Turkish background including many Kurds, have improved in the last few months after serious tensions over the arrests of German citizens in Turkey and a crackdown on dissent in Ankara after a 2016 failed coup.
Turkish President Recep Tayyip Erdogan has repeatedly criticized Germany for not fighting more effectively against the PKK and the movement of Fetullah Gulen, an Islamic cleric based in the US whom Ankara blames for the attempted coup in 2016.
law/jm (AP, dpa, Reuters)