The German capital Berlin is scrambling to ban a planned rally against Islamists by neo-Nazis and self-styled soccer hooligans after rioting in Cologne in which 49 police officers were injured.
The disturbances coincided with growing concern that Western-led air strikes to stop the advance of Islamic State insurgents in Syria and Iraq are radicalizing some young people with Muslim immigrant backgrounds in Germany and elsewhere.
Sunday's clashes, when some 4,000 hooligans - many drunk - and neo-Nazis hurled objects at police who responded with pepper spray and water cannons, also raised fears of violent youths with no political agenda joining forces with a racist group.
The hooligans - as they term themselves - want to stage a protest against ultra-conservative Islamic Salafists at Berlin's Brandenburg Gate on Nov. 15, a week after the capital celebrates the 25th anniversary of the fall of the Berlin Wall.
Berlin's senator for interior affairs Frank Henkel told ARD television he had heard talk of 10,000 people wanting to attend.
“We will do everything we can to ban the demonstration,” said Henkel. “We are experiencing a new quality, a new dimension of street violence and militancy. [In Cologne] it was clear from the start that it was not about a political statement but seeking physical clashes, especially with the police.”
However, although German courts regularly ban marches by neo-Nazi groups, Henkel said this should be decided on a case-by-case basis rather than trying to impose a long-term ban.
Germany's domestic intelligence agency, the BfV, monitors neo-Nazis and the far left but does not currently keep watch on football hooligans, perceiving most as apolitical.
“They see their values, Western values, if I can put it like that, as beer drinking and beating people up,” said BfV president Hans-Georg Maassen. “We have, however, established that there were a lot of right-wing extremists trying to mix in with the hooligans [in Cologne].”
The German security services have warned of an increased risk of street violence between rival radical groups while sounding an alarm about a rising number of Islamist militants inside the country ready to join Islamic State.
Salafists advocate a puritanical form of Islam and the BfV says their numbers in Germany are rising, along with the number of potential recruits for Islamic State.
The BfV estimates that 450 people have traveled to the region from Germany to join radical jihadist forces.
The marchers in Cologne bellowed “Hooligans against Salafists” and “Foreigners out!”
Germany is sending arms to regional Kurdish forces in Iraq to help them fight Islamic State while the United States is spearheading coalition air strikes on the insurgents.