Spain’s Constitutional Court has overruled Catalonia’s declaration of independence. The autonomous region declared independence 12 days ago, plunging the region into instability.

The highest legal authority in Spain has officially overruled Catalonia’s unilateral declaration of independence.

Spain’s Constitutional Court gave a ruling on the declaration on Wednesday afternoon, according to the Reuters news agency.

The statement, taken after a vote by the Catalan parliament, plunged the region into crisis 12 days ago.

Spain dissolved the Catalan parliament, and fired its president and all of its deputies immediately after the October 27 declaration after invoking an article that allows Madrid to take control over the autonomous region.

The Spanish High Court also remanded into custody eight senior members of the Catalan government, including Vice President Oriol Junqueras, without bail last week.

Meanwhile, Catalan leader Carles Puigdemont is in Brussels with four other former cabinet ministers, where they said they would run the government "indefinitely."

The five politicians handed themselves into Belgian authorities last week, after Spain issued a warrant for their arrest. A Belgian court subsequently released them.

Spain also called for elections in Catalonia to take place on December 21, and said Puigdemont could take part if he wanted. Catalonia's pro-independence parties, however, failed to agree on a unity ticket before the deadline to register coalitions, Reuters reported on Tuesday.