Barcelona, Spain (CNN) Supporters of Catalan independence maintained their standoff with the Spanish government Saturday as they prepared to hold a fiercely disputed referendum.

Parents occupied schools in a bid to prevent police from restricting access to their use Sunday as polling stations. Their actions came a day after huge crowds massed in Barcelona, the regional capital, for a final campaign rally by independence supporters, many waving the distinctive Catalan flag.

Catalan President Carles Puigdemont gave a rousing call for people to vote despite the obstacles.

"We are people who have experience with difficulties, and every difficultly makes us stronger," he said. "Friends, so that victory is definite, on Sunday, let's dress up in referendum (clothes) and leave home prepared to change history, to end the process and start progress, social progress, economic progress and cultural and national progress."

Catalonia: What you need to know

Catalonia: What you need to know 01:10

Catalonia: What you need to know

Spain's central government has issued stern warnings against the referendum , which the country's highest court has barred as unconstitutional. It has seized ballot papers and drafted thousands of extra police, or Guardia Civil, in a bid to prevent it.

On Saturday, Guardia Civil officers raided the Catalan government's telecommunications and information technology center, Joan Maria Piqué, the international communications director for the government of Catalonia, told CNN.

The raid was intended to stop the use of vote-counting software linked to Sunday's referendum, Piqué said, adding that the Catalan government has an alternative to the software. A day earlier, a Spanish court ordered Google to remove a voting location app from its Play Store, claiming it was helping Catalan separatists organize in advance of the vote.

Parents organize a youth fair to take place inside a Barcelona school over the weekend in hopes of ensuring it remains open until Sunday.

Across the region, 2,315 polling stations are expected to open, mostly inside schools, Catalan government spokesman Jordi Turull told reporters Friday.

Spain's central government said Friday that the regional Catalan police, the Mossos d'Esquadra, would be responsible for removing people from polling stations in a nonviolent way. The Guardia Civil were stationed on ships in the port of Barcelona in case they were needed.

Catalan newspapers reported Saturday that the Mossos were going to schools where polling was set to take place and informing people there that if they were not holding legitimate activities, the facilities would be closed.

José Maria Salvatierra, a 55-year-old public worker serving as a polling coordinator at one school, told CNN that parents had planned activities such as soccer games and karaoke discos over the weekend so police would have no legitimate reason to close the schools. Parents had also arranged to sleep in shifts on site as an additional precaution, he said.

"What we want, most of all, is to be able to vote," Salvatierra said. "Then, if 'yes' or 'no', it's up to each person."

Volunteers cook giant dishes of paella to feed those occupying one Barcelona school on Saturday.

Increased tensions

Public support for the referendum within Catalonia, a wealthy region in Spain's northeast, has become increasingly vocal as the vote has neared.

More than 5.3 million voters are on the electoral roll, according to the Catalan government. They will be asked to respond yes or no to the question: "Do you want Catalonia to be an independent state, in the form of a Republic?"

Reflecting the divergent views in Catalonia, a small anti-independence rally was held Saturday in central Barcelona, with participants waving Spanish flags and chanting, "Catalonia is Spain." The crowd of people, some waving Catalonia's flag, but many hoisting Spain's, grew to fill the square in front of city hall. Protestors tried a few times to pull down a pro-referendum banner hanging from city hall and, failing, settled for planting the flag of Spain just below it.

Pro- and anti-independence protests also unfolded this week in Madrid and other cities.

People wave Spanish flags while demonstrating against Catalonia's independence referendum in Barcelona on Saturday.

The Catalan government had not yet made clear how it would respond if the plebiscite results in a "yes" vote. However, Carles Mundó, Catalonia's minister of justice, told reporters there was no minimum participation level required for the referendum result to be binding.

The Catalan government appeared to soften its language somewhat in a news conference Saturday, with officials talking of "peaceful resistance" and a peaceful demonstration of people's democratic rights.

Regardless, Spain's central government insisted the referendum is illegal and must not happen, and that the result would not be recognized.

Tensions have risen as the vote approached, with some Catalans complaining that the central government was seeking to suppress their democratic rights.

A man peels off pro-independence referendum voting posters from a wall on Friday in Barcelona.

'Right to choose'

Catalans who spoke to CNN in Barcelona stressed that they want the freedom to exercise their democratic right to hold a vote, whatever the outcome. Some had come to the University of Barcelona to pick up ballot papers handed out by student associations, in case police confiscated more election material.

"I think it's about democracy and liberty," Ramon Hernández, 80, said. "We want to be able to express our opinion, even the ones who don't want to be independent."

Ramon Hernández, seen in Barcelona, says the referendum is about democracy and liberty.

Added Raul Robert, 43, an industrial engineer: "I don't feel like an independentist nor Catalan, for that matter, but I think every people must be given the right to choose its own destiny. I think it's a matter of democratic rights."

Robert said he'd much rather live in a place allows the democratic right to vote than one that doesn't.

Catalonia has its own regional government, or Generalitat, which already has considerable authority over health care, education and tax collection.

But Catalan nationalists want more, arguing that they are a separate nation with their own history, culture and language and that they should have increased fiscal independence. Many complain that Catalonia ends up subsidizing other parts of Spain.