SANT JOAN DE VILATORRADA, Spain -- Spanish authorities on Friday transferred nine politicians and activists from prisons in Catalonia to the country's capital, Madrid, ahead of a high-stakes trial for their roles in Catalonia's attempt to secede from Spain.

The trial for 12 defendants, including three who are on bail, will begin Feb. 12 at the Supreme Court in Madrid, a Spanish court official told The Associated Press.

Supporters gathered early Friday at the gates of three different prisons in Catalonia, where convoys of regional police emerged ferrying the defendants. Some activists tried to block the vehicles by throwing themselves on the road, but were quickly removed by police.

The trial is expected to last about 3 months, the court official said.

The defendants could be imprisoned for decades if they end up convicted of rebellion, the gravest of the charges. They could also be fined if they were found guilty of misusing public funds in the secessionist attempt.

Defence lawyers say they should be acquitted.

The "trial of the century," as it's been labeled by the Spanish media, has taken on a high political significance. Separatists in the prosperous northeastern region have made clear that they will use the trial to prove that they are being tried for their ideas.

The proceedings will be public and televised.

The charges stem from the autumn of 2017, when Catalan separatists pushed ahead with a banned independence referendum and a violent police crackdown attempted to stop it.

In Spain's deepest political crisis in decades, the unauthorized independence vote still went ahead. Separatist Catalan lawmakers declared victory and made a unilateral independence declaration 26 days later, but received no international recognition.

The court said members of the conservative Spanish government at the time of the breakaway bid will be called to testify. They include former Prime Minister Mariano Rajoy and former Deputy Prime Minister Soraya Saenz de Santamaria as well as a number of ministers, lawmakers and former Spanish and Catalan officials.

Regional Catalan President Quim Torra spoke publicly Friday to throw his weight behind the separatists.

Speaking in English and Catalan, Torra urged European institutions to support the 12 defendants, saying "no crime has been committed" because they were simply exercising their democratic rights. He urged the Spanish government of Prime Minister Pedro Sanchez to negotiate the Catalan region's self-determination.

Sanchez has said he is open to granting Catalonia greater powers of self-rule but insists the Constitution doesn't allow Catalonia to break away.

Government spokeswoman Isabel Celaa urged Torra to tone down his words and permit the two sides to move closer.

At the upcoming trial, prosecutors and state attorneys will be joined on the prosecution bench by a far-right party that has recently emerged in Spanish politics. The nationalist Vox party wants to use the trial to showcase its hard-line stance against regional secessionists and its defence of Spanish unity ahead of elections for the European Parliament and local offices in May.

Several more politicians, police officers and elected officials will also be tried in lower courts for their roles in the secession attempt.

The Catalan leader at the time, Carles Puigdemont, is campaigning for Catalonia's independence from Belgium, where he has avoided extradition to Spain. The court in Spain has refused to allow Puigdemont to testify via video-conference.

Among those who remained behind and were put in custody are his former No. 2, ex-Catalan Vice-President Oriol Junqueras; activist-turned-politician Jordi Sanchez and the former speaker of Catalonia's regional parliament, Carme Forcadell.

The nine defendants on Friday were grouped at Brians 2, a penitentiary 40 kilometres (24 miles) west of Barcelona, before being escorted by the Civil Guard to two prisons in Madrid.

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Parra reported from Madrid. Barry Hatton contributed from Lisbon, Portugal.