Tens of thousands of Catalan pro-independence supporters packed streets in Barcelona to demand the release of officials who pushed for the region to split from Spain.
At the march, organised by Catalonia’s two main grassroots independence groups, activists waved Catalan flags and held yellow banners with the word “Freedom”.
After the Catalan government declared independence on 27 October, Madrid dismissed the region’s leader Carles Puigdemont, his administration and the parliament.
Catalonia’s autonomy was suspended and Madrid called for new elections on 21 December.
Mr Puigdemont is currently in self-imposed exile in Belgium awaiting a hearing on possible extradition back to Spain after Madrid issued an EU-wide warrant.
The disputed President of Catalonia has told Sky News the Spanish state has “damaged democracy in order to stop independence”.
Four of his former ministers are also with him in Brussels, claiming they may not get a fair trial back home.
Eight members of the cabinet are currently detained in Spain on charges of sedition, rebellion and misuse of public funds.
Another six sacked officials including parliament speaker Carme Forcadell were granted bail this week on similar charges by the supreme court.
At the march outside parliament, 63-year-old Pep Morales, who thought separatist parties would win next month’s election, said: “Look at all the people here.”
“The independence movement is still going strong,” he added.
The result of the 1 October referendum was 90% for ‘yes’, but it was secured on a low turnout of just over 40%. Most anti-independence voters boycotted the vote.
The poll was declared illegal by Spain, and the crisis has caused concern in the EU amid uncertainty over the fate of the region’s 7.5 million people.