A demonstration organized by German far-right groups has erupted into violence in the heart of the western city of Cologne.

Police say they are using water cannons and pepper spray in an attempt to calm the situation after protesters threw bottles and fireworks at officers.

Police spokesman Andre Fassbender says there are no figures on injuries or arrests yet.

Some 2,000 people attended Sunday's demonstration against Islamic extremism. It was organized by neo-Nazi groups and members of Germany's football hooligan scene.