Huddled under umbrellas in the rainy German capital, the protesters walked from Brandenburg Gate to the justice ministry, carrying banners that read “Free Puigdemont and the Catalan political prisoners” and “Spain is not a democracy”.
Many also waved Catalonia's blue, yellow and red separatist flag as they took part in the rally organised by the German branch of the Catalan National Assembly (ANC), a major grassroots pro-independence group.
“What we want to say is simply: free our elected Catalan politicians,” said 34-year-old marketing worker Monica Zaldivar, who accused the Spanish government of using the courts to go after Catalan leaders instead of trying to find a political solution.
“For me, it's about democracy in Spain,” she said.
One of the organisers, Ferran Cornella, told AFP he estimated the crowd to number “400 or 500” people, while police gave a tally of around 200 demonstrators.
Puigdemont was arrested by German highway police last Sunday as he was travelling from Finland back to Belgium, where has been living in self-imposed exile since Catalonia's failed independence bid last October.
The detention came two days after a Spanish judge issued international arrest warrants for Puigdemont and other fugitive separatist leaders.
They have been ordered to stand trial for rebellion, misuse of public funds and disobeying the state for organising last year's referendum on Catalan independence, which Madrid deemed illegal.
Puigdemont's arrest has sent tensions soaring at home, triggering a wave of protests in the northeastern Spanish region.
Demonstrations in Barcelona last Sunday descended into violence, leaving around 100 people lightly injured in clashes with police.
German judges have ordered Puigdemont to remain in custody in the northern town of Neumünster as they mull Spain's request for him to be handed over.
They have 60 days to make a decision.
German media say the request has been complicated by the fact that rebellion, which carries a maximum penalty of 30 years in jail in Spain, is not a crime under German law.
In a message relayed through his lawyer earlier this week, Puigdemont vowed to “never surrender” and continue his fight for regional independence.
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