Berlin: German security agencies are on alert for signs of violence against Turkish facilities in Berlin, Stuttgart and other cities, the Interior Ministry said, after fires damaged several Turkish-run mosques over the weekend.

Firefighters battled for more than 90 minutes to extinguish a blaze at the Koca Sinan mosque in Berlin early on Sunday. It was the latest in a series of incidents police say may be linked to demonstrations by hundreds of people against Turkey's military operation in the northern Syrian region of Afrin aimed at sweeping the Syrian Kurdish YPG militia from the Turkish border.

"The events in the region can stoke passions among Kurds living here in Germany," a ministry spokeswoman said, noting that conflicts between Turks and Kurds were also playing out in Germany, which is home to about 3 million people with ties to Turkey, including many ethnic Kurds.

The ministry appealed to demonstrators to avoid violence, and said protesters needed to abide by German laws.

"The security agencies are constantly exchanging information with regard to current events," she added.