BARCELONA, Spain -- Spain's constitutional Court on Thursday ordered Catalonia's parliament to suspend a planned session next week during which separatist lawmakers wanted to declare independence -- further fueling Spain's worst political crisis in decades.

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, 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, 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."

Rajoy's remarks were the first since Sunday, when Catalonia held a banned referendum on independence, amid police violence. Puigdemont said the results of the vote validated the push to secede.

On Wednesday, 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, Spanish private news agency Europa Press reported citing internal sources.

Banco Sabadell couldn't be immediately reached for comment.

News of the possible move pushed the bank's shares up more than 6 per cent in Thursday's trading, following heavy losses of almost 10 per cent this week.

On Wednesday, Spanish stocks suffered the biggest drop since the Brexit referendum in the U.K. last year. The main Madrid stock index is down 2.5 per cent this week in volatile trading.

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 per cent since announcing Wednesday it would move its headquarters out of Catalonia.

About 40 per cent 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 Monday to evaluate the results of the referendum. Pro-independence lawmakers say the declaration will be made then.

As the deadline approaches, the clamour for dialogue and mediation in the crisis is gathering momentum, although Rajoy's government seems to be sticking to its stance of not talking to those wanting to break up the country.

Barcelona Mayor Ada Colau called on European institutions to consider setting up a task force of experts to mediate after meeting consular representatives of European countries.

Officials in the European Union have called for dialogue, but have supported Spain's conservative government in blaming the political crisis on Catalonia's regional government.

On Wednesday, Barcelona lawyers set up a commission to promote talks bringing together trade unions, economists and even the city's famed Barcelona soccer club.

Pablo Iglesias, the leader of the Spanish opposition party Podemos, called Rajoy and urged him to seek mediation. But Rajoy insists that regional president Carles Puigdemont must first drop the threat of declaring independence, which was seen by some as a slight easing of his opposition to talks.

Rajoy has been under pressure to act without further tarnishing his image or inflaming separatist sentiment in the region, where a strong cultural identity has mixed with years of grievances for what many Catalans see as an unfair economic treatment of the region, one of Spain's richest.

On Thursday, some of the additional police officers deployed in the region were seen checking out of a hotel in the coastal town of Pineda de Mar amid two sets of protesters -- one side yelling at them to leave and another showing support.

Protests mushroomed following the Oct. 1 vote, condemning police violence and urging the "occupying forces," as many demonstrators have called them, to leave Catalonia.

Many other demonstrations have taken place around the country in support of Spanish unity.

The government has praised the police response, calling it proportionate.

Spain's Interior Ministry said the departures Thursday had been previously scheduled, as contracts ended with some of the hotels hosting the police reinforcements.

Because of difficulties in finding accommodations on land, some of the more than 5,000 extra forces deployed in the region have slept on three ferries docked in Barcelona and nearby Tarragona.

Giles contributed from Madrid.