A far-left separatist party in Catalonia has called for “mass civil disobedience” after the Spanish central government sought to crush the region’s independence movement by triggering its so-called “nuclear option” over the weekend.

Spanish Prime Minister Mariano Rajoy announced plans to dissolve the Catalan parliament on Saturday, under a previously unused article of the country’s constitution. He vowed to curtail some of the freedoms of Catalonia’s parliament, fire some of its political players and hold regional elections within six months.

In response, the CUP party — a key ally to the separatist coalition in Catalonia’s regional parliament — said Monday that Rajoy’s unprecedented move to intervene in the running of the region was “the greatest aggression against the civil individual and collective rights of the Catalan people” since the dictatorship of General Francisco Franco, who died in 1975.

Spain was plunged into its worst constitutional crisis in decades after Catalonia held an independence referendum on October 1. Of the 43 percent of Catalans reported to have taken part, around 90 percent are believed to have voted in favor of independence.

The Catalan government, led by Carles Puigdemont, has consistently argued that the “yes” vote provides the Catalonian region with a mandate to announce a split from Spain. However, Madrid has consistently dismissed the legitimacy of the outcome, saying the referendum was illegal.

Several days after the vote, Spain’s government apologized to injured demonstrators hurt during police efforts to stop the referendum taking place. The Catalan health department said 1,066 people required medical attention after police attempted to seize ballot boxes and disperse voters.

What happens next?

Rajoy’s announcement over the weekend, which coincided with nearly half a million people protesting in Barcelona, Catalonia’s biggest city, still requires the approval of the upper house of the Senate. A vote is scheduled to take place in Spain’s upper houses of parliament on Friday.

However, the Catalan parliament is reportedly expected to meet on the same day to debate the crackdown. Puigdemont has said Catalonia will not accept direct rule.

While Catalan separatists have called for outside intervention as a means to potentially help end Spain’s ongoing political crisis, it has not yet come close to producing a solution. The European Union has said the matter of regional independence is an internal affair for Spain to decide.

Almost 7.5 million people live in Catalonia, an economic powerhouse situated in the northeast of the country. Spain’s total population is nearly 49 million.

What is the so-called ‘nuclear option’?

Spain’s leader is looking to employ Article 155 of the constitution. This says that any largely autonomous community, such as Catalonia, must fulfil its obligations to the Spanish state, or else risk having its powers taken away.

Rajoy said the central government had four goals in seeking to implement this strategy — to return to legality; to restore normality and coexistence in the region; continue Catalonia’s economic recovery; and to hold regional elections as soon as possible.