(Salafis in Germany cite freedom of religion to allow them to distribute free copies of the Koran, as here on Potsdamer Platz square in downtown Berlin, April 14, 2012. Other Salafis later attacked Bonn police trying to keep order when far-right protesters invoke their right to protest against them. REUTERS/Tobias Schwarz)

Ultra-conservative Salafist Muslims turned on police protecting anti-Islam protesters in the western German city of Bonn, injuring 29 officers, two of them seriously, police said in a statement on Sunday.

Authorities arrested 109 people, among them a 25-year-old man suspected of stabbing two police officers, after angry clashes on Saturday between protesters waving banners showing cartoons of the Prophet Mohammad and a large group of Salafists.

Local media said 500-600 Salafists faced off with 30 anti-Islam protesters.

The Salafists in recent weeks have handed out thousands of Korans, translated into German, to non-Muslims, sparking a highly charged debate in Germany.

North Rhine-Westphalia Interior Minister Ralf Jaeger pledged to identify all Salafists prepared to use violence, so that authorities could take swifter action in future.