Spanish Prime Minister Mariano Rajoy has gone on National TV appealing to Catalan separatists to abandon their plans for a referendum on 1 October.
He asked the region’s government to give up its “escalation of radicalism and disobedience”.
Speaking from his official residence, the Moncloa Palace, Rajoy said there was “still time to avoid greater evils” and he urged Catalan leaders to observe the law.
Earlier on Wednesday, Catalan President Carles Puigdemont accused the central government of effectively suspending devolution after it moved to seize control of regional finances to stop them being used to fund the referendum.
“Spain has de facto suspended the self-government of Catalonia and has applied a de facto state of emergency,” he said.
“We believe that the Spanish government has crossed the red line that separated it from repressive authoritarian regimes and has become a democratic shame.”
Protests in Barcelona and other Catalan towns, such as Tarragona and Berga, continued into the night
The Spanish authorities have sought to stop the vote, which they regard as illegal, by seizing voting materials.
Police searches in the Catalan capital, Barcelona, sparked a mass street protest on Wednesday.