Last month, several Catalan officials were arrested and charged over their part in organising the referendum.
Catalan leader Carles Puigdemont has insisted he will push ahead with a unilerateral declaration of independence and could even declare secession tomorrow at an extraordinary session of the Catalan Parliament.
"The Spanish Government have a postion about the legality of this referendum which you're all aware of". It would deprive Spain of a fifth of its economic output and more than a quarter of its exports.
Weighing against that is the decision of several large businesses, including Catalonia's top two banks, to pull out of the region amid the uncertainty over its future.
Residents, some 7.5 million people, have also been able to maintain their national language: Catalan. The majority of the region's unionists boycotted the October 1 referendum, which was banned by Madrid and disrupted by a violent police crackdown.
"If independence were to be recognized - which is not something that's being discussed - the most immediate outcome would be that (Catalonia) automatically left the European Union", she said. Spanish law bans such representations if they are used to incite acts of violence. Spanish borrowing costs fell to a one-week low and the main share index .IBEX touched a week high.
Puigdemont is scheduled to address the regional parliament on Tuesday evening.More news: Keys to Victory: Rams vs Seahawks
He also said that the Catalan movement aimed at obtaining more autonomy for the region should be peaceful and be conducted "within the framework of treaties". Turn-out for the referendum was 43 percent. Catalans calling themselves a "silent majority" opposed to leaving Spain broke their silence after a week of mounting anxiety over the country's worst political crisis in a generation.
At least 350,000 people joined a unionist rally in Barcelona on Sunday, after recent massive rallies by separatists and democracy activists in the city.
European Economics Commissioner Pierre Moscovici, asked about the economic impact of the Catalan debate, said the Spanish constitutional order must be respected. "I believe we know what Spaniards think, and they should know that the government too is clear about what it has to do".
Catalans speak up against a split: Social media was once again full of images of protests in the Catalan capital of Barcelona, but this time from those who don't want to see a breakaway region.
"If there were a declaration of independence it would be unilateral and it wouldn't be recognised", France's minister for European affairs Nathalie Loiseau said.
"We will apply what the law says", he said, according to a partial transcript released by TV3.
Catalonia accounts for almost a fifth of Spain's economy, and leads all regions in producing 25% of the country's exports, CNNMoney reports.