Pro-unity protesters gathered for a rally in Catalonia's capital Barcelona on Sunday, two days after regional lawmakers voted to break away from Spain, plunging the country into an unprecedented political crisis.

As protesters gathered for the march, the deputy president of the region's now-deposed government lashed out against Madrid over what he called a "coup d'etat".

"The president of the country is and will remain Carles Puigdemont," his deputy Oriol Junqueras wrote in Catalan newspaper El Punt Avui.

Junqueras used the word "country" to refer to Catalonia, whose lawmakers pushed Spain into uncharted waters Friday with a vote to declare the region independent.

"We cannot recognise the coup d'etat against Catalonia, nor any of the anti-democratic decisions that the PP (Prime Minister Mariano Rajoy's ruling Popular Party) is adopting by remote control from Madrid," Junqueras wrote.

He signed the article as the "vice president of the government of Catalonia".

There were fears on Saturday that Mr Puigdemont faced imminent arrest after he continued to defy Madrid by standing by the declaration of independence he led in Catalonia’s parliament.

Mr Puigdemont could face more than 30 years in prison and sources from the Spanish public prosecutor’s office said they would demand that he be remanded in custody as soon as he is arrested.

Spain’s prosecution service was preparing accusations of rebellion and misuse of public funds against Mr Puigdemont for going ahead with an illegal referendum on independence for Catalonia, held on October 1 amid scenes of police violence against hundreds of voters.