Riot police used batons in Barcelona after ruling
Protests after Spain detains independence leaders
Thousands of protesters have taken to the streets after Spain's supreme court detained five separatist leaders for their role in a bid for independence last year.
The court also issued international arrest warrants for six other Catalan figures who have fled abroad, including former regional president Carles Puigdemont.
Twenty-four protesters were lightly injured in clashes with police, emergency services said.
Riot police used batons to keep the demonstrators away from the federal government offices in Barcelona.
The protest had been called on Thursday, by the radical Committees for the Defence of the Republic (CDR), before the court decisions were announced.
Spain's Supreme Court said on Friday it would prosecute 13 key Catalan separatists for "rebellion", a crime which carries a maximum penalty of 30 years in jail.
Five people were held in custody, including Catalan presidential candidate Jordi Turull who was due Saturday to seek a second round vote in the regional parliament, after failing to be elected earlier in the week.
A Supreme Court judge held former Catalan parliament president Carme Forcadell and three former regional ministers alongside Turull.
Judge Pablo Llarena decided that the five posed a flight risk, after Marta Rovira became the latest leading pro-independence figure to flee abroad to escape charges.
Rovira ignored the summons and announced she was taking "the road to exile".
The deputy leader of the leftwing separatist ERC party, whose chief is currently in jail, is currently in Switzerland, according to Spanish media.
Llarena also issued international arrest warrants for Mr Puigdemont, who is in self-imposed exile in Belgium along with four of his former ministers.
All five left Spain following a proclamation of independence for Catalonia in October. One of them, Clara Ponsati, has since moved on to Scotland.
Four other separatists had already been detained by the Spanish authorities.
In total 25 people, the core of the movement, have been indicted over last year's independence drive.