Barcelona: Masses of flag-waving demonstrators demanding Catalonia's independence and the release from prison of separatist leaders jammed downtown Barcelona on Friday as the northeastern Spanish region endured its fifth straight night of unrest.

Protesters stand and crouch behind barricades on the fifth day of protests over the conviction of a dozen Catalan independence leaders in Barcelona, Spain. Credit:AP

Chaotic scenes of violence erupted after more than a half million protesters, including families with children, marched in the Catalan capital, according to local police. Many were clad in pro-independence 'estelada' flags and shouted "Independence!" and "Freedom for political prisoners!"

Some of them had walked for three days in five massive "freedom marches" from towns across the northeastern Spanish region. They converged on Barcelona, a city of 1.6 million people, and joined students and workers who also took to the streets during a 24-hour general strike.

But at night, police resorted again to rubber bullets and, for the first time this week, to tear gas and water cannons to repel masked youths hurling cobblestones and flammable bottles, building barricades and setting dozens of bonfires with large garbage bins.