Pro-independence leaders in Catalonia have vowed to press ahead with plans to break away from Spain, despite a decision by the Constitutional Court to suspend the secession process.
Spain's government earlier appealed to the Constitutional Court to intervene.
The court warned Catalan leaders they needed to comply with the order.
"If they fail to comply with the suspension, they may commit disobedience," read the ruling by the Madrid-based high court.
Catalonia's regional parliament on Monday passed a motion to start the secession process, stating an aim of independence within 18 months, and giving 30 days to start legislation on a Catalan constitution, treasury and social security system.
Read more: Catalonia vows to continue independence bid despite court ruling - BBC Net