MADRID - Thousands of demonstrators descended on the Barcelona-El Prat airport after the Spanish Supreme Court handed down on Monday sentences of between 13 and 9 years to seven former members of the Catalan regional government for their roles in the Oct 1, 2017 independence referendum.

The referendum was declared illegal by the Spanish Constitutional Court.

The Spanish Airports and Air Navigation (AENA) confirmed on Monday that 108 flights had been cancelled at the Barcelona airport due to the protests.

The metro and train lines to the airport were also closed due to demonstrations, while the high-speed rail link between Barcelona and the city of Girona (north-east Spain) and the roads connecting the city to the airport have also been blocked by demonstrators.

Main roads in Barcelona were also cut by demonstrators and thousands of protestors demonstrated in the central Plaza de Catalonia and Plaza Sant Jaume to protest at the sentences on Monday night.

Emergency services confirmed that 56 people were injured in clashes with police, with 10 taken to hospital.

The referendum in the northeast region of Spain, which seeks the independence of Catalonia, was a social and political movement, which the Spanish government and Constitutional Court insists was illegal.