Spain on Wednesday took control of the finances of Catalonia, an autonomous community in the country’s east, to stop funds being used for an independence referendum. The Spanish police seized millions of ballot papers that were to be used for the vote, AFP reported. Police officers also raided Catalan government offices, and arrested 12 senior officials, according to The Guardian.

Catalan President Carles Puigdemont has accused the Spanish government of effectively suspending the region’s autonomy. He described the raids as a “a co-ordinated police assault” that showed Madrid “has suspended the self-government and applied a de facto state of emergency”, The Guardian quoted him as saying.

Thousands took to the streets in Barcelona on Wednesday to protest against the detention of the Catalan government officials.

Why Spain is against the referendum?

Tensions between Madrid and Catalonia have been high since the Spanish government blocked Barcelona’s planned referendum to split from it. On September 6, Puigdemont had signed a decree that called for a “self-determination referendum of Catalonia” on October 1. But the next day, Spain’s Constitutional Court suspended the referendum after a legal challenge by Prime Minister Mariano Rajoy. Spain said it was contrary to the Constitution.

Spain did not stop an earlier vote in November 2014, but this time the Catalan leadership plans a declaration of independence within 48 hours of a yes vote, the BBC reported.