Barcelona (AFP) - Catalan leader Carles Puigdemont said Saturday he and his supporters would not "give up" their rights, speaking on the eve of an independence vote that Madrid has banned and is trying hard to block.

By Saturday, the interior ministry said it had sealed most of the 2,315 polling stations in the wealthy northeastern Spanish region in an effort to prevent Sunday's referendum.

However, teachers, parents, students and activists have leapt into action, defying warnings of repercussions by occupying at least 160 schools designated as polling stations.

In an interview with AFP, Puigdemont insisted that his government had "everything in place so that everything takes place normally", vowing that supporters of the referendum would not "go home" or give up on their rights.

But he also called on mediation over the crisis that pits his separatist executive against Madrid in what has become one of the biggest crises to hit Spain in decades.

"If the yes wins, if the no wins -- in any scenario there must be mediation, because things aren't working" he told AFP.

Puigdemont did not call on any specific person, organisation or country to mediate Catalonia's dispute over its place within Spain, but he hinted the EU may be well placed to do so.

"I think that from now it would be logical for the EU to actively monitor (the situation) and actively take an interest," he said.

The crisis has sown divisions among Catalans, with the region deeply split on independence, even if a large majority want to be allowed to settle the matter in a legal vote.

Further afield, Spaniards the country over are worried.

In Spain's major cities, Madrid, Sevilla, Santander, Alicante, Valencia and Malaga, thousands protested for Spanish unity, and thousands also rallied in Barcelona, the Catalan capital.

"We shouldn't have got to this point. We've arrived at a point of no return," said Fernando Cepeda, a 58-year-old engineer, a Spanish flag tied around his waist in front of Madrid's city hall.

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- Pyjama parties, Zumba dance -

Authorities have been racing against the clock to prevent the vote ruled unconstitutional by Spain's courts.

For days, they have been seizing electoral items such as ballot papers while prosecutors have ordered the closure of websites linked to the vote and the detention of key members of the team organising the referendum.

But those for the vote have mobilised. Farmers and firefighters have vowed to protect polling stations.

And on Friday, as children finished their school day, parents, kids, teachers and activists rushed to occupy building designated as polling stations to stop police from closing them.

Many used the Telegram messaging app to get organised, said an AFP correspondent who saw some of the messages.

Some schools imagined innovative ways to circumvent an order that public spaces cannot be used for the referendum by organising leisure activities all over the weekend, from kids' pyjama parties to volleyball games.

Barcelona's Joan Brossa high school, for instance, advertised a series of activities including film screenings, football matches and Zumba dance fitness classes.

Enric Millo, the central government representative in Catalonia, said earlier Saturday that 163 of the polling stations were already occupied when they were sealed off. As a result, those inside were allowed to leave but no one could enter.

AFP reporters, however, visited several occupied schools where people were free to go in and out freely, indicating there may be more occupied buildings that have yet to be sealed off.

A regional government source said there were "around 200 occupied centres" in the municipality of Barcelona alone.

Millo said police had also gone to the Catalan government's communications hub in Barcelona on Saturday, cutting its connections with polling stations as well as a software that could have allowed "an online vote."

- Fear of unrest -

Catalan separatist leaders and organisers of "committees to protect the referendum" have stressed that everyone must remain peaceful.

In one incident, though, someone fired a pellet gun on Friday night at a group of people standing in front of an occupied high school in the Catalan town of Manlleu, lightly injuring three people, police said.

The Mossos d'Esquadra Catalan police have warned about the risk of "disruption of public order" if efforts are made to prevent people from casting ballots.

Madrid has sent thousands of extra police officers from other forces to Catalonia -- which accounts for one fifth of Spain's economy -- to stop the referendum from happening.