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 be prosecuted for failing to halt the session.
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.
Executives in Banco Sabadell, one of Catalonia’s largest banks, are to decide later Thursday whether to move the company’s official registration out of Barcelona to remain under European regulations even if regional separatist authorities succeed in declaring independence.
The news pushed the bank’s shares up 4 percent, following heavy losses of almost 10 percent 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 percent this week in volatile trading.
In a sign that investors are taking seriously the financial risks of independence, the biotech firm Oryzon Genomics saw its shares jump 23 percent since announcing Wednesday it would move its headquarters out of Catalonia.
About 40 percent 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 would then be made.
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.
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.