The simmering tensions in Turkey's Kurdish southeast are not only playing out along the country's border with Iraq, where the military has amassed tens of thousands of troops following renewed clashes with Kurdish rebels holed up in Iraq's mountainous north. They're also spilling onto the streets of European cities from Berlin to Brussels to Innsbruck, Austria.

This weekend, authorities are braced for another round of protests in the German capital, where two weeks ago Turkish ultranationalists attacked a Kurdish cultural center, wielding machetes and injuring dozens of people. Last weekend, some 600 mainly Kurdish protesters returned to Hermannplatz – a square in Berlin's heavily immigrant Neukölln district – to inform the public of their view: that Turkey is still repressing the Kurdish people.

"It's been going on for years. The recent threat of Turkish military incursions into northern Iraq to attack us is just the last straw," says Ahmed, a young man handing out pro-Kurdish leaflets.

With 2.5 million residents of Turkish origin, including an estimated 400,000 who identify themselves as Kurdish, Germany is home to the largest expatriate community from Turkey and is perhaps the most visible European arena for Turkish-Kurd tensions. The expat violence has prompted politicians including the German interior minister to warn against the Kurdish conflict spilling over to Germany and other European countries.

So far there has been no indication that the clashes were planned. But that does not mean that no group has an interest in using them for their purposes, says Süleyman Bağ, Berlin correspondent for Zaman, a conservative daily newspaper in Turkey. In particular he refers to the Kurdish Workers Party (PKK), an organization outlawed in Turkey and Germany and classed by the US and the European Union as a terrorist group.

Taking a softer stand on Kurdish interests than previous administrations, Turkey's ruling Justice and Development party (AKP) has made unprecedented gains in Kurdish strongholds in recent elections at the expense of Kurdish parties. The trend extends to Kurdish rebel groups such as the PKK, which has become a lot less popular with Kurds, maintains Mr. Bağ. By "internationalizing" the Kurdish conflict the PKK hopes to mobilize new support, he says.

Meanwhile, Kurdish representatives in Germany charge that German-Turkish politicians are doing Turkey's bidding. Some of them have used the clashes in Berlin for one-sided and unwarranted attacks on the PKK, says Ayten Kaplan of Germany's Federation of Kurdish Clubs, referring to statements of a prominent member of Germany's Green party. "I would have hoped these politicians exert a moderating influence instead of polarizing further," she says.

In Turkey's capital, Ankara, the clashes in Germany have so far met with a muted response from Turkish politicians. While Prime Minister Recep Tayyip Erdoğan is arguably more occupied with the conflict in northern Iraq, his government is likely to follow closely what happens on the streets in Germany for another reason.

Talks over Turkey's possible accession to the European Union (EU) are presently close to a standstill and popular opinion in a number of large EU countries including Germany is less than enthusiastic about Turkey becoming an EU member. Turks and Kurds battling it out on the streets of EU capitals would make things worse.

"Ankara has no interest in seeing these tensions escalate," says Faruk Sen, director at the Center for Turkey Studies at the University of Essen in western Germany. But even if they do, he says, the real losers will be Turks and Kurds in Germany. In a country that has seen heated debates over immigration for years, further violence "would play right into the hands of those who are convinced that all efforts to integrate people of Turkish origin into German society have been a complete failure."