Spanish Prime Minister Mariano Rajoy has vowed to do everything in his power to prevent Catalan secession following a banned referendum in the region, which remains deeply divided over independence.
He held an emergency cabinet meeting after Catalonia's president Carles Puigdemont announced on Tuesday that he had accepted the mandate for "Catalonia to become an independent state."
Rajoy told lawmakers in Madrid he was giving Puigdemont until Monday to decide if he really wanted to take the path of independence.
"It is very important that Puigdemont clarify for the rest of Spaniards if he declared independence yesterday or not," he said.
Rajoy said if Puigdemont did push ahead with secession, the central government would give him until October 19 to reconsider, before suspending Catalonia's regional autonomy.
The deadline sets the clock ticking on Spain's most serious political emergency since its return to democracy four decades ago.
World leaders are watching closely and uncertainty over the fate of the region of 7.5 million people has damaged business confidence, with several listed firms already moving their legal headquarters to Madrid.
Madrid rejects mediation
Puigdemont said the referendum had given him a mandate for independence but immediately asked regional lawmakers to suspend the declaration to allow for negotiations with the central government.
Rajoy has said he will not negotiate on anything until the separatists abandon their independence drive, and rejected calls for mediation in the crisis.
"There is no mediation possible between democratic law and disobedience, illegality," he told parliament on Wednesday.
Rajoy on Wednesday triggered constitution article 155, which allows Madrid to impose control over its devolved regions -- an unprecedented move many fear could lead to unrest.
The article provides a warning period for any region attempting to leave Spain.
The leader of the opposition Socialist Party, Pedro Sanchez, backed Rajoy's demand for clarification in order to "get out of the swamp".
Independence a 'fairy tale'
While separatist leaders say 90 percent of voters opted to split from Spain in the October plebiscite, less than half of the region's eligible voters actually turned out.
The drive to break Catalonia away from Spain has raised concern for stability in a European Union still coming to terms with Britain's shock decision to leave the bloc.
The EU on Wednesday urged "full respect of the Spanish constitutional order".
German Foreign Minister Sigmar Gabriel said any unilateral independence move would be "irresponsible" and France said it would not recognise Catalonia's "illegal" bid for statehood.
Crowds of thousands gathered outside the parliament building in Barcelona on Tuesday ahead of Puigdemont's speech, waving Catalan flags and banners and screaming "democracy" in the hope of witnessing history in the making.
But reaction among separatists in Catalonia was mixed.
Barcelona resident Maria Rosa Bertran said she was against a delayed secession, which meant "suffering a longer agony. Indecision and uncertainty is the worst thing that can happen to us," she told AFP.
Puigdemont insisted Wednesday that "the majority of Catalan people want Catalonia as an independent state."
In an interview with CNN, he suggested that Madrid and separatists try to identify possible mediators: "Maybe, it could help (us) talk."
But Rajoy dismissed Puigdemont's push as "a fairytale".
"It is not peaceful, it is not free, it will not be recognised by Europe and now everyone knows it will have costs," he told lawmakers.
Madrid stocks, buoyed by both sides' play for time, rallied Wednesday, with the capital's benchmark IBEX 35 index of top companies closed up 1.34 percent.
Following his declaration to parliament, Puigdemont and his allies signed an independence declaration outside the chamber, but its legal validity was unclear.
"I did not expect independence to be declared today because of all the processes that the government of Spain has begun, both with police actions and with threats," said Barcelona student Marc Cazes on Tuesday.
Police violence against voters during the referendum vote sparkedinternational concern an turned many Catalans against the central government.
Catalonia, which accounts for about one-fifth of Spain's economic output, already enjoys significant powers over matters such as education and healthcare.
But Spain's economic strains during the world's financial crisis, coupled with resentment that the region pays more in taxes than it receives in investments and transfers from Madrid, have helped push the cause of secession from the fringes of Catalan politics to centre stage.
Catalan demands for sovereignty date back centuries. In 1934 regional president Lluis Companys declared a "Catalan state" but surrendered 10 hours later to the Spanish army.