CATALAN protesters have massed at Barcelona’s airport to protest sentences handed down to pro- independence leaders – despite brutal police counter measures.

Thousands upon thousands of demonstrators have gathered at El prat aiport.

Crowds also poured onto the streets of Barcelona and Girona after Catalan activists and politicians were sentenced to a cumulative 100 years in prison.

READ MORE: 100 years of jail time for pro-independence Catalan leaders

As the news broke, protesters mobilised, blocking streets in Barcelona and elsewhere as police braced for what activists said would be a mass response of civil disobedience.

The airport authority said at least 20 flights had been cancelled due to the demonstrations.

Footage quickly emerged of protesters being beaten with batons as police attempted to break up the crowds.

But a huge column of people continued to stream towards the airport.

Videos posted on social media later in the evening appeared to show the police attempts had been in vain, with huge crowds singing in unison inside and outside of the airport.

Nicola Sturgeon and Ian Blackford have joined several other SNP politicians in condemning the jail sentences for Catalan leaders.

READ MORE: Nicola Sturgeon responds to sentencing of Catalan leaders

SNP MPs also joined protests outside of the Spanish embassy in London.

“What happened to democratically elected Catalan politicians and civic leaders today was beyond unacceptable,” Douglas Chapman tweeted.

Spain's Supreme Court convicted 12 former Catalan politicians and activists for their roles in a secession bid in 2017.

The court sentenced former Catalan regional vice president Oriol Junqueras to 13 years for sedition and misuse of public funds.

READ MORE: Europe, now it's up to you: Full statement from Catalonia’s Foreign Minister

Eight others received lengthy prison terms in Catalonia's attempt to break away from Spain following an illegal independence referendum, while three received lesser sentences.

Although prosecutors had requested convictions for the more severe crime of rebellion, which under Spanish law implies the use of violence to subvert the constitutional order, judges convicted nine of sedition, implying that they promoted public disorder to subvert the law.

Grassroots pro-secession groups had said that if any of the defendants were found guilty they would organise protests and "peaceful civil disobedience". Spanish authorities deployed hundreds of extra police to the region in anticipation of the ruling.