ANKARA (Reuters) - Turkish President Tayyip Erdogan said on Thursday Germany had become a haven for terrorists and would be "judged by history", accusing it of failing to root out supporters of a U.S.-based cleric Ankara blames for July's failed military coup.

Erdogan said Germany had long harbored militants from the Kurdistan Workers Party (PKK), which has waged a three-decade insurgency for Kurdish autonomy, and far-leftists from the DHKP-C, which has carried out armed attacks in Turkey.

"We are concerned that Germany, which has protected the PKK and DHKP-C for years, has become the backyard of the Gulenist terror organization," Erdogan said, referring to the network of U.S.-based cleric Fethullah Gulen.

"We don't have any expectations from Germany but you will be judged in history for abetting terrorism ... Germany has become an important haven for terrorists," he told a ceremony at his palace in the capital Ankara.

Ankara blames Gulen for the coup attempt and has suspended or dismissed more than 110,000 of his suspected followers from the civil service, security forces and other institutions in a crackdown. Gulen has denied involvement in the putsch.

German Justice Minister Heiko Maas told reporters on Tuesday that he did not want to judge whether the Gulenist movement was political in nature or not. He also said Berlin would not extradite suspects if they faced political charges.

"That would certainly not happen," he said. For any extradition to take place, there had to be firm indications of "classic criminal activity".

Erdogan said he was concerned by Germany's reluctance, and warned that "the menace of terrorism would come back and strike it like a boomerang."

(Reporting by Ece Toksabay and Tuvan Gumrukcu; Madeline Chambers in Berlin; Editing by Nick Tattersall)