The Committee for the Defence of the Republic (CDR), a Catalan pro-independence group, blocked several roads on Tuesday to protest the arrest of former leader, Carles Puigdemont.
Traffic was halted on several motorways and highways and on the Diagonal, one of the main avenues of Barcelona.
People held banners calling for “freedom’’ for “political prisoners.’’
Apart from Puigdemont, several Catalan secessionist figures are in pre-trial detention in Spain, including his ex-deputy Oriol Junqueras and a new candidate for the Catalan presidency, Jordi Turull.
The CDR also called a “general strike’’ at 6 pm (1600 GMT) in the city’s Placa de Joan Peiro, a square in the southern Sants neighbourhood.
Puigdemont was detained by German police on Sunday at a highway rest stop near the Danish border, as he drove from Finland to Belgium, where he has been living since fleeing from Spain.
He left the country just before the Spanish government ousted his government in reaction to an Oct.1 referendum on independence that was deemed illegal by the constitutional court.
More than 90 per cent of votes cast were in favour of a break-up from Spain, but pro-Union Catalans mostly boycotted the ballot, and turnout was less than 50 per cent.
The Spanish government called new regional elections in December, in which secessionist parties won again, but have since been unable to form a new government, partly due to Spanish arrest warrants.(dpa/NAN)