The Spanish government has vowed to block the move
Catalonia's regional government has called a date for a referendum on a proposed split from Spain.
The move reestablishes conflict with Madrid, which maintains such a vote is illegal and against the constitution.
The Catalan president, Carles Puigdemont, said that voters in the unilateral referendum on October 1st would be asked the question: “Do you want Catalonia to be an independent country in the form of a republic?”
Puigdemont’s pro-sovereignty administration insists the wealthy north-eastern region has a political, economic and cultural right to self-determination.
But the Spanish government is implacably opposed to secession, arguing that it is a violation of the constitution, and has vowed to use all possible means to stop the referendum from being held.
Dismissing the announcement, Spain’s deputy prime minister, Soraya Sáenz de Santamaría said it was an empty threat.
“They can announce a referendum as many times as they want and put it back as many weeks as they want, and hold as many events as they want, but the referendum is not going to take place," she said.
Under Article 155 of Spain’s constitution, Madrid has the power to intervene directly in the running of Catalonia’s regional government, and force it to drop the vote and obey the law.
This could involve sending in the police or suspending the regional government’s ruling authority in the industrial region.
The populous and wealthy region accounts for around a fifth of Spain’s economic output. It has its own language and capital, Barcelona.
Like Spain’s other 16 autonomous regions, Catalans already have power over health and education spending. The region says the central government takes much more than it gives back under Spain’s complicated system of budget transfers.
This feeling contributed to a surge of pro-independence fervour during Spain’s worst years of recession at the beginning of this decade.
Pro-independence campaigners staged a symbolic ballot on splitting from Spain in 2014, following the Scottish referendum concerning a split from the UK.
Previous secessionist challenges in Catalonia were blocked by Spain’s conservative government.
Support for independence within the region has dwindled - the last poll showed that 44.3 percent backed a split from Spain, while 48.5 want to continue with the status quo.
However, polls show a majority of Catalans do want to hold a referendum on the question of independence.