Cologne (dpa) - At a mass demonstration in Cologne against the Turkish military offensive in northern Syria, today (11.00 clock), more than 20,000 people are expected, according to police.

Since several thousand participants would be considered violent, check a ban on the demo, the Cologne police said on Friday. This could also be imposed shortly before the start of the event. The organizers had registered about 15,000 participants, many Kurds are expected. Called several left alliances, including the party The Left supports the call.

The exchange with other security authorities have received new information, said the Cologne police chief on Friday. Across Europe had been called in the Kurdish milieu to the protests in Cologne. "We expect parts of the young people to be armed," he said. It can also be assumed that protesters from the Turkish nationalist milieu wanted to mix with the Kurds.

Head of operations Klaus Rüschenschmidt announced that in addition to several hundreds and water cannons, police units were being deployed that had been specially trained to intervene in riots. Special forces are also to be on the spot in Cologne - which hopefully would not have to intervene, as Rüschenschmidt emphasized. "But I'm afraid it will happen."

The officials worried about the protection of Turkish-influenced institutions. "Even a kebab can be compromised," Jacob said. No route guidance is possible in Cologne, which does not provide any potential stimuli for violent demonstrators, added Rüschenschmidt.

If there was a ban on the demonstration, there was a danger that violent groups would still gather in Cologne. In addition, the freedom of assembly is a high, worth protecting property. Jacob again called for peaceful behavior. "Violence in the Middle East can not be combated by force in Cologne," he said.

The organizers of the demonstration expected on Friday evening, no riots, as a spokeswoman for the Kurdish umbrella organizations from the organizing team of the German Press Agency said. There is no evidence of violence.

Even Cologne Mayor Henriette Reker called on Friday to demonstrate peacefully. "For all applies: freedom of expression has its place in Cologne, but who seeks violence, has lost nothing in Cologne," wrote the non-party politician on Twitter.

From the central meeting points Ebertplatz and Chlodwigplatz, participants are expected to draw a joint final rally on the Hohenzollernring - one of the main thoroughfares in the center of Cologne - according to prior planning. For the demonstration, large parts of the city center are closed to through traffic. One expects considerable restrictions, the city had communicated a few days ago. Motorists should drive around the city center or plan extra time.

In protests in Bottrop and Lüdenscheid it had come this week in similar demos already riots with injured. NRW Interior Minister Herbert Reul (CDU) said that "the limit of our tolerance was clearly exceeded".