A senior Catalan official said on Saturday that an offer of talks with Madrid over his region's independence push was aimed at negotiating secession from Spain, not halting it.

The central government has given the Catalan president Carles Puigdemont until next Thursday to abandon designs on independence, failing which it may trigger unprecedented constitutional steps that could see Madrid take control of the semi-autonomous region.

Puigdemont's number two Oriol Junqueras said Saturday that dialogue with the central government “must have at its heart the formation of the (Catalan) republic and our commitment to independence”.

“We need to be clear that the best way of achieving an independent republic is to talk to everyone, including the international community,” Junqueras told members of his Esquerra Republicana de Catalunya (ERC) party in Barcelona.

The wealthy region's drive to break away from Spain has unleashed the country's worst political crisis in a generation.

After staging a banned referendum on October 1, in which separatists say 90 per cent of people voted for secession, Catalan president Carles Puigdemont said last week he had accepted a “mandate for Catalonia to become an independent state”.

He immediately suspended the declaration, however, ostensibly to allow time for dialogue with Madrid. Prime Minister Mariano Rajoy, who has repeatedly said Catalan independence is not up for discussion, responded by giving Puigdemont a deadline to make up his mind.

The journalist-turned-politician now has until Monday morning to declare Catalonia independent or not. If he does, he has until October 19 to change his mind or Rajoy has said Madrid will start taking direct control over the semi-autonomous region.

As the standoff drags on, dozens of companies have moved their legal headquarters out of Catalonia, and concerns are rising that the crisis will severely damage the region's economy and even dampen Spain's growth prospects.

540 businesses leaving Catalonia

Spain's deputy prime minister Soraya Saenz de Santamaria warned Friday that if “there is no quick solution, we see ourselves having to lower economic forecasts for 2018”.

The International Monetary fund has also voiced concern and ratings agency Standard and Poor's said the region's economy risked sliding into recession if the crisis persists.

Spain's Association of Registrars said Friday that 540 firms had sought to relocate their legal addresses from Catalonia from October 2-11.

Puigdemont is under pressure from Madrid and EU states to remain part of Spain but also from his allies in the Catalan parliament who want the region to break away immediately.

Adding to tensions, Catalonia is deeply divided over independence, and those who want to stay in Spain are increasingly making their voices heard, having staged two mass rallies in just five days.

“The Spanish government is rejecting every day,” the chance of international mediation in the crisis, Junquera said.

But Madrid has never countenanced talks on a push it insists violates the constitution.

It is ready to invoke article 155 of Spanish law, a never-before-seen provision that allows Madrid to take direct control of its devolved regions if it deems them to be acting against the national interest.

The head of Rajoy's Popular Party in Catalonia, Xavier Garcia Albiol, said Friday that measures could include changing the structure of the local Mossos d'Esquadra police force, as well as imposing more direct rule over education.

'Return to normality'

Officials in Madrid are waiting to see what Puigdemont decides by the Monday deadline, but it is thought the Catalan leader could deliver what the central government deems another “ambiguous” response to the question of independence.

“If that's the case, that will show that he doesn't want dialogue and so the Spanish government will need to take necessary measures to return to normality,” said interior minister Juan Ignacio Zoido Alvarez on Saturday.

Junqueras, who is under investigation for civil disobedience, abuse of office and misuse of public funds over the referendum, said Catalans needed to be united “for the good of (Catalonia).”