Hundreds of tractors rolled into Barcelona to protect polling stations ahead of the 'banned' Catalan independence referendum this Sunday.

Striking images capture the moment more than 500 of the heavy vehicles were driven in to protect the '2,315 polling stations all over the region' - intended for the referendum that is said to have been banned by officials in Madrid.

Independence supporters, many wearing the colours of FC Barcelona or flying the estelada flag clung from the tractors in a loud, forceful show of strength.

Thousands of people gather at the final pro-independence rally at Plaza Espana tonight ahead of Sunday's referendum vote in Barcelona

Two young women watch on at the pro-independence rally at Plaza Espana in Barcelona tonight

Thousands of people cheer and wave esteledas, or Catalonia independence flags, during the 'Yes' vote closing campaign in Barcelona tonight

The protest came as police seized more than 2.5million ballots in a Catalan town in a bid to scupper the referendum.

'The Guardia Civil (police force) seized 2.5 million ballots, four million envelopes and 100 ballot boxes in a warehouse in Igualada,' said a source, speaking on condition of anonymity.

The source said the company involved alleged the ballot boxes were 'for elections at FC Barcelona', without giving further details.

A spokesman for the football club confirmed that the company had indeed provided FC Barcelona with ballot boxes for elections of its president in the past, but could not comment further.

Driving slowly along the city's broad boulevards in support, many of the tractors carried the Catalan pro-independence flag, called the 'estelada,' to the headquarters of the regional government

Striking images capture the moment more than 500 tractors were driven into Barcelona for the Catalan independence referendum which has been banned by officials in Madrid

Driving slowly along the city's broad boulevards in support, many of the tractors carried the Catalan pro-independence flag -the estelada - to the headquarters of the regional government.

Similar tractor protests were held across Catalonia. While a conservative group in Madrid has set up a large, mock ballot box in the centre of the city and urged people to vote on whether they want Catalonia to remain a part of Spain.

The act in Madrid's emblematic Puerta del Sol square on Friday came in criticism of Catalonia's planned referendum on secession.

Despite this, the Spanish government has pledged to stop the referendum, which it says is unconstitutional.

Supports queue up to cheer on the agricultural workers proudly flying the estelada through Barcelona - despite fears the Spanish government could block the vote

Court orders Google to delete app used for Catalan vote Catalonia's High Court today ordered Google to delete an application that it said Catalan separatists were using to spread information about the disputed independence vote this Sunday. The court said the On Votar 1-Oct application on the Google Play smartphone app store opposed an order in September from Spain's Constitutional Court to suspend the referendum while it determined its legality. The court also ordered Google to block any future applications developed by the gmail address Onvotar1oct@gmail.com, according to a written ruling. Nobody at Google in Spain was immediately available to comment. Advertisement

Meanwhile, pro-separatist Catalans today occupied several schools in Barcelona, which are designated to be polling stations, to ensure the vote will go ahead, according to AFP reporters at the scene.

Two schools in the centre of Barcelona were occupied, according to the journalists, while a 'platform of open schools for the referendum' posted on Twitter images of several occupied polling stations.

According to laws passed by local government, should Catalan leaders see a successful referendum vote, they may declare themselves independent from Spain within 48 hours.

Speaking to BBC News, Catalan President Carles Puigdemont said: 'After the official proclamation of the results, which should take a few days there is a period of 48 hours to proclaim independence but this does not exclude the possibility of us making yet another appeal on the night of the 1st for the need to sit down and talk to resolve this politically.

'The wealthy region of 7.5 million people in north-eastern Spain has its own language and culture, and a high degree of autonomy, but it is not recognised as a separate nation by the Spanish state.'

According to laws passed by local government, should Catalan leaders see a successful referendum vote, they may declare themselves independent from Spain within 48 hours

Independence supporters, many wearing the colours of FC Barcelona - the region's successful football club - clung from the tractors in a loud, forceful show of strength. While the estelada was draped around dozens of supporters

More than 500 of the tractors rolled around the cities roundabout cheered on by hundreds more vocal supporters ahead of Sunday's vote

Meanwhile, Catalonia's separatist leader has defended plans to stage the 'banned' referendum - despite being unable to explain how independence from Spain would work.

Carles Puigdemont wants supporters to defy Spanish efforts to block the vote on Sunday by turning out at polling stations that police have been ordered to keep shut.

The 54-year-old has described Madrid's attempts to ban the referendum as 'authoritarian repression', 'a violation of our basic rights' and 'the fall of democracy'.

The north-eastern Spain has its own language and culture, and a high degree of autonomy, but it is not recognised as a separate nation by the Spanish state

Catalonia's separatist leader Carles Puigdemont (pictured) has defended plans to stage a 'banned' referendum - despite being unable to explain how independence from Spain would work

Carles Puigdemont wants supporters to defy Spanish efforts to block the vote on Sunday by turning out at polling stations that police have been ordered to keep shut. Separatists are pictured holding a demonstration in Barcelona yesterday

But he was unable to explain how a new Catalan state would be formed and how it would function - especially given the challenge of trying to gain recognition from the European Union in the event of an independence declaration.

He told the New York Times: 'There is no button that you push and the next day you become independent.'

But defending plans to hold the referendum, he told the newspaper: 'If you're hungry, you know that you want to eat. You don't know what's on the menu — perhaps it's not your favorite dish — but you will eat.'

Pro-independence groups the Catalan National Assembly (ANC) said on Thursday that people should form queues if they found police guarding voting stations. The tractor protest is an attempt to protect voting stations that Catalonians fear will be blocked

Raising her fist in support, one independence supporter on a tractor grinned happily while posing for a photograph with dozens of tractors rolling behind her

Last night, Catalan separatists urged supporters to defy Spanish efforts to block the referendum, calling for peaceful turnouts at polling stations.

Pro-independence groups the Catalan National Assembly (ANC) and Omnium said on Thursday that people should form queues if they found police guarding voting stations, amid concerns that frustrations over an event progressively stripped of any meaningful political impact could erupt into street unrest.

Tackling one of the biggest political crises to hit Spain since democracy was restored in the 1970s after decades of dictatorship, authorities in Madrid have declared the referendum unconstitutional and told police to ensure no votes are cast.

Catalan separatists urged supporters to defy Spanish efforts to block the referendum, calling for peaceful turnouts at polling stations

Around 4,000 state police from other regions have been deployed to prevent the vote and maintain security. Fire fighters are pictured taking part in a demonstration in Barcelona on Thursday

Catalan independence More than 2,300 polling stations are ready for the Catalan independence referendum slated for Sunday but banned by Madrid, the regional separatist government said today. Spokesman Jordi Turull told reporters there would be '2,315 polling stations all over the region' and more than 7,200 people involved in holding the referendum despite a crackdown by Madrid. 'A total of 5.3 million Catalans who have the right to vote are called to vote,' he said. At the end of the press briefing, Turull, Catalan Vice-President Oriol Junqueras and Raul Romeva, in charge of foreign relations for the Catalan executive, unveiled a plastic ballot box with a regional government stamp on it. Police have for days been seizing electoral items such as ballot papers as they follow orders to stop the referendum from taking place, after courts ruled it unconstitutional. But they had failed to find any ballot boxes until Thursday, when police seized 100 from a warehouse in a Catalan town, although the company in charge alleged they were destined for internal elections at the FC Barcelona football club. Over the past few days, judges and prosecutors have also ordered the closure of websites linked to the vote and the detention of key members of the team organising the referendum. On Wednesday a judge ordered police to prevent public buildings from being used as polling stations. Advertisement

The rich northeastern region is pressing ahead, and Puigdemont - who has labelled the government's response anti-democratic - said a week ago he had contingency plans in place to ensure the vote would take place.

But ANC and Omnium said Catalonia's priority for Sunday should be to present a responsible and united face to the world - even if that meant forming long queues without actually voting.

'Peaceful resistance, zero violence... If you can't access the voting stations, by no means should you respond with violence,' ANC said in an internal document distributed to members.

'Above all, bear in mind this is not a demonstration but a giant queue. The picture of millions of people queuing with a ballot paper in their hand will be more impressive.'

With both groups having strong track records of non-violent protest, the biggest risk of civil disturbance appeared to lie with members of foreign anarchist groups, who local newspapers including El Confidencial and El Espanol said had arrived in Barcelona.

If they approach any of the more than 2,500 voting stations across Catalonia, they will encounter a stepped-up police.

Around 4,000 state police from other regions have been deployed to prevent the vote and maintain security. They will join 5,000 state police based in the region and 17,000 local police, or Mossos d'Esquadra.

The Mossos have said the order to close voting stations increased the risk of confrontation between demonstrators and police, a worry shared on Thursday by two United Nations experts.

Around 4,000 state police from other regions have been deployed to prevent the vote and maintain security. They will join 5,000 state police based in the region and 17,000 local police, or Mossos d'Esquadra

'We are concerned that this order and the accompanying rhetoric may heighten tensions and social unrest,' said David Kaye, Special Rapporteur on the promotion and protection of the right to freedom of opinion and expression, and Alfred de Zayas, independent expert on the promotion of a democratic and equitable international order.

Following a meeting a Barcelona of senior security officials, Spain's junior Interior Minister Jose Antonio Nieto confirmed no vote would be allowed, though the government would not prevent people from demonstrating.

'On Sunday, it will be possible to celebrate, everybody in a different way, through a picnic or a demonstration, and to express a sentiment but there will be no breach of the law,' he told a news conference.

ANC said voters should show 'institutional dignity' and form queues without staging a 'spectacle'.