Spain's top court has ordered the suspension of a planned session in Catalonia's parliament, in which regional leaders were expected to unilaterally announce a split from Spain.

The Constitutional Court on Thursday ruled to block the parliamentary meeting called for Monday while it considers an appeal made against it, according to a spokesperson.

The session had been called to debate the results of Catalonia's banned October 1 referendum, which returned a 90 percent vote in favour of breaking away from Spain, according to local officials.

READ MORE: Catalonia referendum - Latest updates

The vote had been declared illegal by the central government in Madrid.

Al Jazeera's Karl Penhaul, reporting from Catalonia's capital, Barcelona, said the court's decision "really has taken a lot of people by surprise; nobody really foresaw this move".

He added, "This is unknown territory, it also does mark a ratcheting up of the pressure both by the Spanish central government and the Spanish courts on Catalonia to try and stop its bid to break away from the rest of Spain."

Catalonia's President Carles Puigdemont said on Wednesday that the Catalan regional government "will show our best face to apply the results of the referendum" following the vote, which witnessed violent clashes between national police and civilians that left almost 900 people injured.

READ MORE: Spain king 'ignoring millions of Catalans' - Puigdemont

Mariano Rajoy, the Spanish prime minister, may be forced to use article 155 of Spain's 1978 constitution if the Catalan parliament opts to push ahead with declaring a split from Madrid. The article allows the central government to suspend the region's autonomy and remove officials from office.

Spain's King Felipe VI called on Tuesday for the national government to "ensure constitutional order" is maintained.

Criticising separatist Catalonians, he accused regional separatists of risking "the economic and social stability of Catalonia and all of Spain".

"They have placed themselves totally outside the law and democracy," he said.