Nine separatist leaders from Catalonia have been jailed by Spain's Supreme Court for their role in a failed bid for independence.

Key points: All defendants were acquitted of rebellion, the gravest charge

All defendants were acquitted of rebellion, the gravest charge The former head of Catalonia's regional government says he is appalled by the verdict

The former head of Catalonia's regional government says he is appalled by the verdict An opinion poll in July showed 48.3pc of Catalans were against secession, 44pc in favour

The longest prison term — 13 years — went to the former vice-president of the Catalan regional government, Oriol Junqueras. The others were jailed for between nine and 13 years.

The court convicted Junqueras and the eight other leaders of sedition and misuse of public funds in relation to holding a banned referendum and short-lived independence declaration in October 2017.

Three other defendants were given fines but not jail time after being found guilty of disobedience.

All defendants were acquitted of the gravest charge, rebellion, but other leading separatists were quick to call the ruling an "atrocity" and an "attack on democracy".

Protests in wake of landmark ruling

Hundreds of students and civil servants protested in different parts of Barcelona, the capital of the Catalonian region, following the sentencing on Monday (local time).

"Today, they have violated all their rights. It is horrible that Europe doesn't act," 60-year-old civil servant Deni Saball said while protesting in the street.

"I don't want to be European. I don't want to be Spanish."

Spanish authorities deployed hundreds of extra police to the region in anticipation of the ruling.

After the ruling was published, the CDR grassroots movement tweeted: "It's time to rise up against the authoritarian fascism of the Spanish state and its accomplices. It is time for the #RevoltaPopular (popular revolt)."

The government has said it is ready to take direct control of Catalonia as it did in 2017 if secessionist leaders break the law.

Junqueras says independence is 'closer than ever'

Following his sentencing, Junqueras said Catalonia's independence from Spain was "closer than ever".

Former Catalan leader Carles Puigdemont called the jail sentences an "atrocity". ( AP: Michael Sohn, file )

"We Catalans do not have an alternative," he said.

Former Catalan regional president Carles Puigdemont, who fled Spain to Belgium along with several others following the failed secession bid, wrote on Twitter that he was appalled by the verdict.

"A total of 100 year of prison. How horrible. Now more than ever, we will be you and your families. For the future of our sons and daughters. For democracy. For Europe. For Catalonia," he said.

Monday's ruling is likely to colour Spain's national election on November — the country's fourth in four years — and influence the direction taken by the separatist movement.

An opinion poll in July showed 48.3 per cent of Catalans were against secession and 44 per cent were in favour.

AP/Reuters