Some 2,500 people including hardline football fans and far right extremists from across Germany had massed in the heart of Cologne's historic centre for a demonstration ostensibly aimed against "Islamist extremism". It was organised by neo-Nazi groups and reportedly included known football hooligans.
They had massed under the banner "Hooligans against Salafists", drawing some 500 leftist and anti-fascist counter protesters in a separate demonstration organised by several human rights organisations to rallying against the far-right demonstration.
Six people were arrested and one of the police officers was seriously hurt, police spokesman Andre Fassbender told the German sports news agency. "Further arrests would likely follow a review of video footage",he said.
Police used batons, pepper spray and water cannon against the protesters, who hurled rocks, bottles and firecrackers at them.
Tensions escalated and right-wing protesters repeatedly yelled "Foreigners out!", national news agency DPA reported.
Earlier this month Kurds in Germany clashed with "radical Muslims"(Salafists) in the northern city of Hamburg and elsewhere, in street protests fuelled by the conflict involving the terrorist group ISIS in northern Iraq and Syria.