Spain's Constitutional Court has suspended a resolution passed by Catalonia's regional assembly that declared the start of a secession process, but the Catalan government has vowed to continue to push ahead with the bid.
Spain's government had filed an appeal with the court with the aim of block ingthe independence drive by the regional assembly and preserving Spanish national unity.
Wednesday's acceptance of the appeal means the resolution is immediately suspended while the judges consider legal arguments.
The Catalan resolution, which was passed on Monday, had set out a plan to form a Catalan republic within 18 months by starting to set up state institutions such as a tax office.
The declaration specifically vowed to ignore the rulings of the Constitutional Court.
The Catalan government immediately vowed to go ahead with the process despite the court ruling.
"The political will of the government of Catalonia is to go ahead with the content of the resolution approved Monday by the Catalan parliament," Neus Munte, the vice president of the Catalan government, told a news conference after the court announced its decision.
Earlier on Wednesday, Spain's Prime Minister Mariano Rajoy had told a news conference: "It's not just a reaction to a motion passed in parliament, this is about defending a whole country,"
The row over Catalonia has escalated dramatically ahead of a national election next month.
The issue has been dominating political campaigns with parties such as Rajoy's ruling centre-right People's Party calling for Spanish unity, and despite one-in-five unemployment, relegating discussion of the economy to a secondary role.
Albert Royo, the Secretary-General of Catalonia's Public Diplomacy Council, told Al Jazeera that the Catalan government is always interested in having proper negotiations and dialogue with the Spanish government.
"We expect to avoid any kind of unilateral movement. But one thing is clear. A democratic mandate has been given to the Catalan Parliament and we will honour this mandate," he said.
A democratic mandate has been given to the Catalan Parliament and we will honor this mandate.
"We foresee a period six to 18 month in order to find a way to have proper negotiations with Madrid."
The highly-industrialised and heavily-populated region in the northeast of Spain makes up about a fifth of the national economic output.
A region with its own language and distinctive culture, it was once a big textile producer and is now trying to reivent itself as a technology hub, while its Mediterranean beaches and art-rich capital Barcelona draw in huge revenues from tourism.
Separatist feeling has been fuelled by demands for greater recognition of Catalonia's cultural identity, so far dismissed by the central state, and demands for a referendum.
Opponents of a Catalan breakaway argue that many other Spanish regions also have a distinct identity and language, and that conceding to one would open a Pandora's box of nationalist demands across the country.
Parties favouring a split from Spain won a majority of seats in the Catalan parliament in September, though they fell just short of half of the vote.
Source: Al Jazeera and agencies