More than 2,500 anti-coal demonstrators protested in the western German town of Kerpen and at a nearby surface-mining site before an upcoming global climate conference in Bonn.
The dpa news agency reported Sunday that a large group of the initial protesters split off to march on the mining site behind a banner reading "We Are Nature Defending Itself."
Riot police scuffled with some of the demonstrators but there were no major incidents reported.
German leader Angela Merkel has been dubbed the "Climate Chancellor" for her ambitious targets for renewable energy, but Germany still gets about 40 percent of its electricity from coal-fired plants.
Before the 2017 U.N. Climate Conference that begins Monday, many protesters have been urging her to move faster to wean the country off coal.