Spanish authorities say lawmakers in the regional Catalonia parliament face criminal prosecution after they endorsed a planned referendum on independence of the region.

Spain’s state prosecutor’s office said on Thursday that criminal charges would be filed against leading members of the Catalan parliament for allowing a vote in the chamber a day earlier on holding the independence referendum on October 1.

A majority of the lawmakers voted in favor of the referendum although representatives of mainstream political parties left the acrimonious session, which saw pro-independence lawmakers singing the Catalan anthem.

Jose Manuel Maza, the state prosecutor general, said he had also requested an investigation by prosecutors into any preparations by the Catalan government to hold the referendum. That would mean any civil servants, including teachers, police officers or administrative workers who contribute to the vote, would risk fines or the loss of their jobs.

Catalonia’s regional head, Carles Puigdemont, has brushed aside threats by the Spanish government, saying the vote would go ahead as planned and its results would be binding regardless of the turnout. A referendum law passed in the regional parliament allows Puigdemont to declare independence for Catalonia within 48 hours of a yes vote.

The government in Madrid punished Catalan politicians for preparing a non-binding ballot on independence in 2014. That referendum saw a low turnout of just over 30 percent.

Spain views Catalan’s efforts for independence as illegal, arguing that it is stipulated in the constitution that the country is indivisible.

Recent polls by the regional government suggest that those opposing independence outnumber the supporters by a low margin. However, local authorities say Catalans would decide on the issue once and for all in the upcoming referendum.