Spanish authorities have been battling separatist activists since 2017 with many independence leaders jailed over controversial charges related to their role in the secession bid.
"This cannot continue. Barcelona does not deserve it," Mayor Ada Colau told reporters, adding that Friday's violence was the worst so far.
It was the biggest gathering since Monday's explosive verdict, which had already brought tens of thousands of independence supporters onto the streets in protest in this wealthy northeast region.
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