"That referendum will not take place because it is illegal", government spokesman Inigo Mendez de Vigo told a news conference, according to Reuters. Catalonia's regional government plans to set a date for a referendum on a split from Spa.
Around two million people in Catalonia voted in favor of secession at the time, although voter turnout was low. Another 10 percent voted in favor of Catalonia becoming a country but chose "No" when asked whether it should be independent from Spain.
Madrid said that it would block any attempt to hold a vote as soon as the referendum announcement was formally rubber-stamped by Catalan authorities. The decision sets up a renewed confrontation with Madrid, which maintains such a vote is illegal and against the constitution.
The region is very much a separate culture already, with a citizenry of about 7.5 million who speak a different language (Catalan) have longed for autonomy.
He said attempts to agree a date and the wording of the question with the Madrid government-which is vehemently opposed to allowing Catalonia to split from Spain-failed and left him with no other choice than moving unilaterally.
The Catalan government accused the Spanish government in Madrid of "abusing its powers to undermine" representatives in the region, while it is unclear how the impending legal battle over the legitimacy of the October poll will play out.
In a symbolic poll held three years ago, more than 80 percent of participants opted for independence, however, only 2.3 million of Catalonia's 5.4 million eligible voters had taken part, reports said.
However, it is still not clear to what lengths the Spanish government would go to prevent the vote from taking place, nor what the reaction of the Catalan administration would be if its referendum plan is blocked.
Such a move, widely seen as a last resort, could involve the closure of schools and public buildings used as polling stations, or the deployment of police to enforce the nationwide legislation. The referendum could force them to choose between obeying their immediate supervisors, and facing consequences for disobeying Spanish law, or sticking with the Spanish Constitution.