Turkey’s foreign ministry summoned Germany’s ambassador in Ankara to protest the country for allowing “terror propaganda” by Kurdish militants, AP reported.

The ministry said late Saturday that a festival in Cologne used “symbols” of the outlawed Kurdistan Workers’ Party or PKK, including pictures of the group’s leader Abdullah Ocalan, imprisoned in Turkey.

The PKK, considered a terror group by Turkey and its Western allies, has been waging a three-decade-long insurgency against the Turkish state. Hostilities between Turkey and Kurdish militants resumed in 2015 after a fragile ceasefire collapsed.

The ministry condemned that permission was given for the festival. The statement said Germany had “a double standard in combatting terror.”

Turkey has repeatedly accused Germany of harboring the PKK and relations have soured in the past year.