BARCELONA (AFP) - Spain ramped up pressure on Catalonia's secessionist leaders Tuesday (Oct 24) as rumblings grew louder of civil resistance to a threatened regional power grab by Madrid.

As the central government moved to depose Catalonia's leadership unless it abandons all secession threats, new ultimatums were given.

Only three days remain to find a solution, before Madrid invokes an article of the constitution designed to rein in rebel regions.

Spain's justice minister insisted that simply calling elections for a new Catalan parliament would not be enough to prevent the takeover of the region's political power and finances.

"Mr Puigdemont's violation of his obligations cannot be resolved merely by calling elections," Rafael Catala told public radio RNE, referring to Catalan leader Carles Puidgemont.

He would need to offer "something extra" - including an unequivocal renouncement of his threat to unilaterally declare Catalonia an independent state.

Pedro Sanz, a senior senator and member of Prime Minister Mariano Rajoy's Popular Party (PP), said Puigdemont has been invited to state his case in Madrid this week.

This could be Thursday, before a senate committee created to draw up a roadmap for seizing power in the region, or at a full Senate sitting Friday set to give final approval for the takeover.

"He (Puigdemont) is willing to go, to challenge this action of the Spanish state," Catalan government spokesman Jordi Turull told journalists.

However, "I cannot give any assurances that it will be practically possible."

Turull also announced that Catalonia intends to go to court to challenge any moves to seize regional power, but was waiting to see exactly which steps Madrid intends to take.

The worst political crisis in Spain in decades was sparked by a banned, and deeply divisive, October 1 independence referendum.

About 90 per cent of participants voted "Yes", according to Catalonia's Generalitat executive, though only about 43 per cent of voters turned out.

Many anti-secessionists stayed away.

The region of 7.5 million people is fiercely protective of its culture, language and autonomy, though polls indicate its inhabitants are divided on whether to break away from Spain.

As a nervous nation waited to see who will blink first in the standoff, the far-left, pro-independence CUP party, which had threatened "massive civil disobedience", scheduled meetings in cities and towns to plot a way forward.

On Monday, the CUP accused Madrid of the "biggest assault" on the Catalan people since Francisco Franco's 1939-1975 dictatorship, which suppressed the region's staunchly-defended autonomy, language and culture.

Firefighters, teachers and students have also warned of strikes and protests, while social media brimmed with "tips" for Catalans planning civil resistance.

"Millions of people are ready to go to the Catalan parliament to prevent the arrest of its president (Puigdemont)", Ruben Wagensberg, founder of "En peu de pau (Stand up for Peace in Catalan) - warning of "a tough campaign" ahead.

The government stuck to its guns.

Under the never-before-used Article 155, Madrid has threatened to depose Catalonia's government, wrest control from its police force, replace the heads of its public news outlets, and take over the entirety of its finances.

After Friday's senate approval, the measures would come into effect once published in the government gazette on Saturday, effectively ousting Puigdemont and his team.

Catalonia's regional parliament will hold a "general debate on the application of Article 155 of the Spanish consitution in Catalonia and its possible effects" two days earlier, on Thursday, the assembly said in a statement. The debate will begin at 10am (8pm Singapore time), it added.

Two options - fresh Catalan elections or a unilateral declaration of independence - were still firmly "on the table", the kingmaker CUP party said Tuesday.

The impacts of the standoff are already been felt.

Spain's companies' registry said nearly 1,400 enterprises have moved their legal headquarters out of Catalonia since the troubles began.

CaixaBank, Spain's third largest lender, said Tuesday its relocation to Valencia was permanent.