Spanish riot police fired rubber bullets and forced their way into activist-held polling stations in Catalonia on Sunday as thousands flooded the streets to vote in an independence referendum banned by Madrid.

Scuffles broke out as police moved in to seal off polling stations and seize ballot boxes to prevent people from voting across the wealthy northeastern region where more than 5.3 million people have been called upon to have their say on independence from Spain.

In central Barcelona, riot police forced their way inside a school to seize ballot boxes, charging at demonstrators who were sitting on the ground blocking their way, witnesses said. 

Witnesses said police in Barcelona also fired rubber bullets, with one demonstrator showing AFP a leg injury he suffered.

Catalan president Carles Puigdemont blasted the "unjustified violence" as emergency services said 38 people were hurt.

Riot police also stormed a polling station near Girona, smashing the glass doors of the sports centre where Puigdemont was due to vote, then cutting a chain to force their way in. 

Inside, they bagged up ballot boxes in black bin liners, wrapping them in police tape before hauling them away. 

But the regional government said Puigdemont had managed to vote anyway, tweeting pictures of him casting his ballot in Cornella del Terri, some 10 kilometres (six miles) away. 

The drama unfolded after a night of tension in which thousands of people, both nervous and excited, had gathered outside polling stations before dawn.

In Barcelona, rows of police vans were in the streets, their blue lights flashing as officers in riot gear, some carrying heavy bolt cutters, walked through the street as crowds thronged the streets outside a polling station.

"Votarem, votarem!" -- Catalan for "We will vote!" -- they chanted, many with their hands in the air. 

- Peaceful resistance - 

As the rain poured down in Barcelona, students and activists who had spent the night in schools gathered outside with locals to "defend" these polling stations from police as cars drove by honking their horns in support.

Catalan television broadcast footage of crowds in towns and villages all over region ahead of the referendum, which has triggered one of the worst political crises in Spain in decades. 

Although the region is divided over independence, most people want to vote on the matter in legal, binding plebiscite.

"The government today is in a position to affirm that we can celebrate the referendum of self-determination -- not as we wanted, but (it will have democratic) guarantees," government spokesman Jordi Turull told reporters. 

The night before the vote, those occuping the polling stations were told to hand out flowers as a sign of peaceful resistance if the police arrived. 

"If someone wants to trouble you, you must remain very calm, smile, practice passive resistance -- we have a lot of carnations to hand out -- and try to delay them as much as possible from taking away our ballot box," said Joan Font, a 37-year-old teacher.

- Ballot boxes hidden -

But the interior ministry said it had started seizing ballot boxes, adding police were "continuing to deploy in Catalonia" to stop the referendum.

Spain's central government is staunchly against the vote, which has been ruled unconstitutional by the courts, and has vowed to stop it from taking place.

On orders of judges and prosecutors, police have seized ballot papers, detained key organisers and shut down websites promoting the vote.

The ballot boxes have been at the centre of attention during the crisis, with many wondering where they were hidden and how they would be delivered to polling stations.

- Occupied schools -

Whatever happens, Sunday's referendum result will not be recognised by Madrid, and almost certainly not by the international community.

Spain's interior ministry on Saturday said police had closed most of the 2,315 polling stations across Catalonia.

But dozens of others were occupied by teachers, parents, students and activists determined to let people in anyway, with schools coming up with innovative ways to stay open over the weekend through by organising activities ranging from kids' pyjama parties to volleyball games.

A regional government source said voting may also happen in other places like health centres and even retirement homes, with people able to cast their ballots at any voting station by using their passports or other identification documents.

Turull said there would be ballots papers at all polling stations but voters could also use home-printed versions downloaded from the internet. 

- Unity protests -

Earlier this week, the Mossos d'Esquadra Catalan police warned about the risk of "disruption of public order" if people were prevented from casting ballots.

Madrid has sent thousands of extra police officers from other forces to Catalonia to stop the referendum from happening.

Spanish Prime Minister Mariano Rajoy's conservative government has come under fire for limiting its response to the crisis to repeating that the referendum is unconstitutional.

"The state needs to explain the benefits of remaining united, instead of repeating all the time that the referendum is illegal," said Rafael Castillo, a 59-year-old engineer at a rally in Madrid, wearing a scarf with the Spanish flag around his neck.

Source: AFP