BARCELONA, Spain (AP) — The mayor of riot-stricken Barcelona pleaded Saturday for calm after violent protests by Catalan separatists rocked Spain's second largest city for a fifth consecutive night.

"This cannot continue. Barcelona does not deserve it," Mayor Ada Colau told reporters, adding that Friday's violence was the worst so far.

Protesters clashed with police again later on Saturday despite efforts by some citizens to mediate by gathering between the two sides. There was also a skirmish between separatist supporters and police in a square in Spain's capital, Madrid. Authorities are bracing for more protests in the coming days.

Radical separatists have fought with police every night in Barcelona and other Catalan cities following huge peaceful protests by people angered by Monday's Supreme Court verdict that sentenced nine separatist leaders to prison for their roles in a failed 2017 secession attempt.

More than 500,000 people gathered in downtown Barcelona on Friday in a massive show of support for the secession movement that is backed by roughly half of the wealthy northeastern region's 5.5 million voters.