Spain's government has lodged a legal bid to stop Catalonia holding an independence referendum, asking the Constitutional Court to veto moves by the regional assembly, Prime Minister Mariano Rajoy has announced.
"There will not be any referendum on October 1," Mr Rajoy told a news conference in Madrid after his weekly cabinet meeting.
The stand-off between Madrid and Barcelona is likely to intensify in the coming weeks as Catalonia's separatist government moves ahead with the vote on breaking with the rest of Spain.
On Wednesday, Catalan lawmakers gave themselves powers to fast-track some laws and preparations for the referendum.
Mr Rajoy said his government had filed a legal bid to block to those reforms with the Constitutional Court, which has previously ruled against secessionist challenges.
Catalonia, a wealthy, populous region in the northeast with its own language and distinct culture, has long harboured an independence movement which grew in intensity during an economic crisis. Pro-secession parties now control its assembly.
Last week the Spanish government told Catalonia it would lose access to some public funds if it uses state money to organise the referendum, and vowed to increase controls on spending.
It is unclear exactly how the vote will happen if, as expected, Spain's Constitutional Court keeps striking down attempts to organise it.
Civil servants such as police officers face a dilemma if the referendum does go ahead, as they risk sanctions from authorities in both Barcelona and in Madrid for not following their commands.
Mr Rajoy, who has been criticised for his inflexible stance on the issue, said he was ready to talk with Barcelona.
"I've always been prepared to have a dialogue over the best way to work with Catalonia's institutions to everyone's benefit," Mr Rajoy said. "I've always been prepared to do that and I am today."