"The impact of the conflict on the Iraqi border can be felt in Berlin," Claudia Schmid from the domestic intelligence services told RBB radio.

"After what happened we can expect further, emotional clashes between Turks and Kurds," she said.

Eighteen police officers were injured in Berlin's Kreuzberg district on Sunday after protestors marching in support of Ankara's threats to launch strikes against Kurdish rebel bases in Iraq began throwing stones and bottles.

Fourteen demonstrators were arrested, according to the DPOIG police union.

It said some of the demonstrators "started a real hunt on Kurds", forcing them to seek refuge in cafes and apartment buildings.

Schmid said supporters of Turkey's notorious far-right Grey Wolves took part in the demonstration in Kreuzberg, which is popular with Turkish immigrants, but that anarchists also joined in the fray.

Police used teargas to break up the protest.

Turkey has seen a wave of protest rallies against the separatist Kurdistan Workers' Party (PKK) since October 21 when day 12 Turkish soldiers were killed in a PKK ambush near the Iraqi border.

The Turkish army claims to have killed more than 60 separatist fighters since then but Ankara's threats to send troops into Iraq to wipe out PKK bases has sparked international tensions.

The PKK, listed as a terrorist group by Ankara and much of the international community, has since 1984 waged a battle for Kurdish self-rule in the east and southeast of the country that has claimed 37,000 lives.

Germany is home to 2.5 million Turks, the biggest Turkish community outside Turkey.

An anti-PKK protest in the Austrian city of Salzburg on Sunday drew about 3,500 people and went off peacefully.