Thousands of people have gathered in the German city of Stuttgart to protest racism and violence against asylum-seekers amid the country's massive influx of migrants.

Saturday's demonstration in the southwestern city was organized by churches, labor unions and other groups to protest attacks on refugees.

Germany registered nearly 1.1 million asylum-seekers last year, and the country saw regular attacks on migrant housing. Tensions have been heightened lately by hundreds of New Year's Eve assaults on women in Cologne and elsewhere that have been blamed largely on foreigners.

Police estimated 7,000 people turned out for the protest, the news agency dpa reported.

Protestant bishop Frank Otfried July told protesters: "Whether it's cowardly arson attacks on homes for asylum-seekers, foreigners being chased or sexist violence, we are showing it the red card."