A Spanish court has suspended a Catalan law that outlined a legal framework for an independent state, a court source said on Tuesday, the day after hundreds of thousands rallied in Barcelona to support secession from Madrid.
Catalan leaders say they will go ahead with the October 1 ballot anyway.
The protest coincides with Catalonia's national day, the "Diada", which marks the fall of Barcelona in the War of the Spanish Succession in 1714 and the region's subsequent loss of institutions and freedoms.
Polls have shown support for independence waning in recent years with those wanting a separate state in a minority. The law rejected by the constitutional court on Tuesday is set to enter into force on October 2 if the pro-independence front wins the referendum to which the majority of Spanisards are however opposed.
However, this year's event had particular significance as a show of strength for the independence movement just three weeks ahead of a referendum on the issue which Madrid has declared illegal and taken steps to obstruct in the courts.
"There are 20 days left (until the referendum) and the mobilisation that prompted this process remains intact", Catalonia's pro-independence president Carles Puigdemont told reporters.
Prime Minister Mariano Rajoy's conservative government has vowed to do everything in his power to stop the referendum.
With Spain's central government promising to block the referendum, the pro-independence camp is keen to show that it can rally its troops - especially after participation in the "Diada" declined previous year.
The Constitutional Court of Spain has suspended another referendum law ratified in the regional parliament of Catalonia as Madrid struggles to block a vote of independence in the region planned for earlier next month. Police have since searched newspaper offices and printers for signs of any preparation for the referendum. But about 70 percent wanted a referendum, to settle the question once and for all.