Madrid.—Spain's Constitutional Court has put a brake on Catalonia's drive for a referendum on independence by opening the door to a legal challenge against the region's claim to sovereignty.

Catalonia's regional parliament in January passed a “declaration of sovereignty” which it said gave Catalonia grounds “to exercise its right to decide” its political future.

The national government rejected efforts by Catalonia's leaders for greater independence, fanned by the economic crisis, and challenged the resolution as a threat to the “unity” of Spain guaranteed by the constitution.

The Constitutional Court in a written decision agreed to hear the government's appeal, meaning the resolution is suspended under Spanish law until the court makes a final ruling. The conservative leader of Catalonia's government and champion of the current drive for sovereignty, Artur Mas, called the decision “highly worrying and deeply disappointing”.

Catalonia, home to 7.5 million people and a major source of exports, has turned in the economic crisis from one of Spain's richest regions to its most indebted.

Proud of their distinct language and culture, many Catalans resent seeing their taxes redistributed to other regions of Spain at a time of recession and spending cuts.

Mas was re-elected in November after calling a snap election in protest at Madrid's refusal to grant Catalonia greater tax powers. He has called for an independence referendum in 2014.