The separatist parties won a slim majority in parliament, a result that is expected to set the stage for return to power of the deposed Catalan President Carles Puigdemont.
The Catalan government accused Madrid of taking “political prisoners” and thousands of protesters gathered along Barcelona’s Diagonal Avenue to call for their release.
Puigdemont made a symbolic declaration of independence last Tuesday, only to suspend it seconds later and call for negotiations with Madrid on the region’s future.
Catalan leader Carles Puigdemont made only a symbolic declaration, claiming a mandate to launch secession but suspending any formal steps to that end.
European leaders have either taken a neutral stance, relegating the conflict to an internal matter for Spain to resolve, or have offered support to the Spanish government.
In Madrid, some socialists have suggested Basque could serve as a model for a compromise that would defuse Spain’s biggest political crisis since a failed coup in 1981.
The Catalan government says more than 90% of people who voted in an October 1 referendum voted in favour of independence from Spain.
Spanish PM Rajoy has remained vague on whether he would use article 155, the nuclear option of the constitution which enables him to sack the regional government.
Mireia Boya, a Catalan lawmaker said a declaration of independence would follow a parliamentary session on Monday to evaluate the results of the October 1.
Late Tuesday, Catalonia’s leader, Carles Puigdemont, said that the region will declare independence in a matter of days.
Police preventing people from voting and firing rubber bullets at protesters, and injuring up to 900, has done deep damage to Spain’s international credibility.
Local courts received several complaints on Sunday against the Catalan police accusing them of inactivity and failing to close polling stations.
The referendum, declared illegal by Spain’s central government, has thrown the country into its worst constitutional crisis in decades.
The dispute has plunged Spain into one of its biggest political crises since the restoration of democracy in the 1970s after decades of military dictatorship.
Catalan leader Carles Puigdemont said he had contingency plans in place to ensure the vote would go ahead, pushing the country closer to political crisis.
Police efforts to stop the referendum have intensified in recent days as the wealthy northeastern region shows no signs of halting it.
City police said that around one million people took part in the police, one of the highest turn-outs in recent years.
A majority voted for the referendum and the legal framework to set up a new state, under which the assembly would declare independence within 48 hours of a “yes” vote.
The stand-off between separatists of the northern region and the central government in Spain deepens as politics remain in limbo after two inconclusive general elections failed to produce a majority.