The Spanish government pledged Friday to take immediate legal action against the regional parliament of Catalonia if the Barcelona-based body approves a proposal to formally start an attempt to break away from the rest of Spain.
Catalonia's parliament has agreed to put the secessionist parties' proposal to a vote Monday, setting itself up for a confrontation with the national government in Madrid, which deems the move a violation of the Spanish Constitution.
Deputy Prime Minister Soraya Saenz de Santamaria said the government will seek the opinion of the Council of State and then call a special Cabinet meeting to announce it is seeking a Constitutional Court ruling.
The separatism proposal was drawn up by the "Together for Yes" pro-independence alliance and the radical leftist CUP party, which between them have 72 seats in Catalonia's 135-member regional parliament following an election in September. The two are in talks to form a new regional government but disagree strongly over who should be president.
Acting regional president Artur Mas has pledged Catalan independence within 18 months if he is chosen as regional president but the CUP has vowed not to support him. The parliament has until Jan. 9 to form a government or call a new election.
Catalonia, a region of 7.5 million people in northeast Spain, is responsible for nearly a fifth of Spain's economic output and is proud of its own culture and language.
Pro-independence sentiment began to swell four years ago at the height of Spain's economic crisis as secessionists claimed Catalonia could do better on its own.
Most polls show Catalans would like a secession referendum but are evenly divided over independence.