THOUSANDS of people backing Catalonia's bid for independence from Spain rallied in Barcelona to demand the release of jailed leaders last night.

Eight former members of Catalonia's cabinet and two activists are locked up while investigations continue into their alleged roles in promoting an illegal declaration of independence last month.

After the declaration Madrid dismissed Catalonia’s Government, dissolved parliament, suspended the region’s autonomy and called new elections for the region next month.

Polls show that Catalonia's 7.5 million residents are split over remaining a part of Spain.

Spain's constitution says the nation is “indivisible” and that questions of national sovereignty pertain to the national parliament in Madrid.

A rebellion investigation stemming from the Spanish region's declaration of independence is ongoing. The Catalan parliament's speaker Carme Forcadell was released on Friday following a night in prison after posting bail.

Forcadell and five other Catalan political figures were quizzed by a judge on Thursday over the regional parliament's October 27 vote to declare independence from Spain followed a disputed referendum.

A judge at the Supreme Court in Madrid on Thursday had ordered her to be held on charges of “rebellion” — which carries a maximum jail term of 30 years — as Spain’s worst political crisis in a generation rumbles on.