Spain's top court has officially ruled that Catalonia's disputed independence referendum was illegal because a regional law that backed it was against Spain's constitution, Independent reported.
The Catalan regional parliament passed the so-called "self-determination referendum law" in early September.
Regional leaders went on to stage the October 1 referendum on whether the region should separate from Spain.
Spain's Constitutional Court had earlier suspended the law temporarily while judges assessed the Spanish government's objection to it. In its ruling on Tuesday, the court said the law was against national sovereignty and the "indissoluble unity of the Spanish nation". The court said that the parliamentary session that approved the law was also illegal.