Tens of thousands have protested against free trade and climate change ahead of the upcoming G-7 summit in Germany.

The leaders of the seven major industrialized nations meet Sunday and Monday at Schloss Elmau, about 100 kilometers (60 miles) south of Munich, to discuss pressing global issues, from curbing global warming to resolving the Ukraine crisis.

Police in Munich said some 30,000 people took part in a rally organized by environmental groups and left-wing parties in the Bavarian capital Thursday. There were no reported incidents.

Authorities are braced for possible violence at a demonstration Saturday in the town of Garmisch-Partenkirchen, close to the summit venue.