Catalonia's government is appealing against plans by Spain's central authorities to directly run the troubled north-eastern region.
Officials want to take the legal battle to international courts.
Regional spokesman Jordi Turull said the appeals will be lodged in Spain's Constitutional Court and Supreme Court against prime minister Mariano Rajoy's decision to sack all members of the Catalan government and curtail powers of the regional parliament.
Spain's Senate is expected to approve Mr Rajoy's plan on Friday, triggering previously untapped constitutional powers to act against regional leaders disobeying the country's top law.
"We are going to respond in a very solid way," Mr Turull said at the end of the regional government's weekly cabinet meeting. "We will exhaust all internal ways in order to turn to the international justice if needed."