As expected on Thursday, Spain's Constitutional Court admitted a central government challenge to the Catalan independence referendum bill, the related electoral committee, and the decree calling the vote, a normal part of the constitutional challenge procedure, that does not constitute a ruling from the justices on the matter itself.

Exceptionally, however, the court also warned more than 1,000 authority figures in Catalonia that they have a duty to uphold the suspension or face possible criminal charges for not doing so.

The list included the First Minister, Carles Puigdemont, and all of his regional ministers; the Speaker of the Catalan Parliament, Carme Forcadell, and her committee; the regional police chief, Josep Lluís Trapero, who has become a well known face across Spain thanks to his role in explaining the terror attacks in Barcelona and Cambril; and several dozen other senior civil servants who will or would be key in some aspect of the referendum process.

The directors general of Catalan public television, TV3, and Cataluña Radio were also warned they had a duty to prevent the vote from being prepared or taking place, along with "the mayors of all of the towns in Catalonia".

The latest Catalan government data, from 2016, lists 948 towns or cities in the region, home to some 7.5 million residents.

On Friday morning, La Vanguardia reported 560 mayors had signed municipal orders allowing their facilities to be used for the vote.

On Twitter on Thursday, many of those municipal leaders enthusiastically posted tweets and photos of themselves doing so.

In the town of Mataró, the Catalan Socialist Party mayor, David Bote Paz, resisted and several hundred pro-independence supporters began a protest outside the town hall. 125,517 people live there, according to the latest National Statistics Institute figures.

Separatist MPs in the Catalan parliament pressed ahead anyway, passing a secession bill shortly before 1 a.m. on Friday morning. It will come into effect if the "yes" vote wins on October 1, but the referendum law it references does not set a minimum turnout level for interpreting the vote's results.

"If the recount of valid votes gives a result of more 'yes' votes than 'no'", says Article 4.4 of the referendum law: "that implies the independence of Catalonia", within 48 hours.

If Catalan separatists manage to hold the vote despite the Constitutional Court and the actions of the Spanish state to prevent it, they will try to declare independence from Spain by October 4.