Spain's Constitutional Court has ordered Catalonia's parliament to suspend a planned session next week during which separatist lawmakers wanted to declare independence.
Catalan regional authorities previously have ignored Constitutional Court orders, so it was not immediately clear if the session would go ahead and if all parties would attend.
The court said its order could be appealed but also warned Catalan parliament speaker Carme Forcadell and other members of the speakers' board that they could face prosecution for failing to halt the session.
Speaking to reporters, Ms Forcadell called the suspension a "violation of freedom of speech".
"I won't allow censorship to enter Parliament," she said without clarifying if the meeting would go ahead or not.
Earlier, Spain's Prime Minister Mariano Rajoy urged the separatist leader of the regional Catalan government, Carles Puigdemont, to cancel plans for declaring independence in order to avoid "greater evils".
In an interview with Spain's official EFE news agency, Mr Rajoy said the solution in Catalonia "is the prompt return to legality and the affirmation, as early as possible, that there will be no unilateral declaration of independence, because that way greater evils will be avoided."
Mr Rajoy's remarks were the first since Sunday, when Catalonia held a banned referendum on independence, amid police violence. Mr Puigdemont said the results of the vote validated the push to secede.
On Wednesday, Mr Puigdemont toned down his defiant stance by calling for mediation in the conflict, although he maintained the plan to declare secession next week.
The court order came as political uncertainty over Catalonia's secession bid started spreading to the economy, with stock markets falling and big Catalan firms relocating or considering a move to elsewhere in Spain.
Banco Sabadell, one of Catalonia's largest banks and Spain's fifth in volume of assets, said in a statement to the Spanish stock regulator on Thursday that it was relocating the bank's base to the eastern city of Alicante.
The move is largely symbolic, given that the headquarters would still remain in the Catalan regional capital, Barcelona, but is aimed at remaining under the protective umbrella of the European Central Bank, sources said.
News of the possible move pushed the bank's shares up more than 6% in Thursday's trading, following heavy losses of almost 10% this week.
Barcelona-based Caixabank, Spain's third largest bank in global volume of assets was expected to study relocation plans in a meeting on Friday, as the government readied a decree to make it easier for Catalan companies to move their base.
In a sign that investors are taking seriously the financial risks of independence, the biotech firm Oryzon Genomics saw its shares jump 23% since announcing on Wednesday it would move its headquarters out of Catalonia.
About 40% of Catalonia's electorate of 5.5 million voted in the divisive referendum marred by violence when police moved in to close polling stations and confiscate ballot boxes.
As expected, the Yes side scored a landslide victory because most of those who want Catalonia to remain in Spain ignored the referendum that the courts had suspended.
Catalan authorities and the Spanish central government are at odds over the legitimacy of the vote. Spain's 1978 Constitution bars any attempt to secede and rules that all Spanish nationals must have a say in the country's sovereignty.
Catalonia's regional parliament called the meeting on Monday to evaluate the results of the referendum. Pro-independence lawmakers say the declaration will be made then.