Masked protesters set fire to dumpsters and threw stones and glass bottles at police, who responded with foam bullets in a street near Camp Nou stadium, while Barcelona and Real Madrid clashed on Wednesday in the first classic of the season.
Forty-six people were slightly injured in the clashes, including eight who needed to be taken to hospital for extra care, local emergency services said. Five people were arrested, a police spokesman said.
Protesters, many carrying Catalan separatist flags, began setting up barricades in the middle of the street, which later burned down after police arrived in dozens of vans, according to an AFP reporter there.
Protesters swung a police van and grabbed the signs they added to the barricade, while some people sought shelter inside a bar. The calm returned to the street when the fans started to leave the stadium at the end of the match, which ended in a 0-0 draw.
Police closed the south exits of the stadium that led to the street where the clashes took place and urged fans to leave the site through the north exits for "security reasons".
A Tsunami Democrat protester is seen holding a sign during protests at the Barcelona-Real Madrid game at Camp Nou. Photography: Robert Marquardt / Getty Images
These were the first violent incidents in Catalonia since October, when Spain's high court arrested nine Catalan separatist leaders for their role in a failed attempt at independence in 2017, triggering days of protests that sometimes ended in clashes with police.
The original equipment in October had to be postponed due to violent demonstrations across the rich northeast region.
Inside the stadium, thousands of fans displayed blue banners with the words 'Spain, sit down and chat', which were given to off-site fans and also carried the words 'Freedom, rights, self-determination'. # 39 ;, as well as the slogan of democratic Tsunami, the protest group promoting the cause of Catalan independence that organized the demonstration.
Protesters began gathering in the four corners of the stadium, blocking traffic four hours before the start. Nearly 5,000 people surrounded the stadium, police said.