Police seized five guns, several knives, marijuana and €180,000 in raids carried out mainly in Barcelona and its suburbs, Catalan regional police said in a statement.

Those arrested on Friday are all suspected members of “los Casuals”, the most violent faction of FC Barcelona’s notorious Boixos Nois group of “ultra” fans, the statement added.

Several suspected leaders of the group were among those arrested.

The police investigation began in November following a violent attack on a bar popular with “ultras” from FC Barcelona’s cross-town rivals Espanyol in which several people were injured.

The authorities indentified six suspects as part of their investigation into the attack who were later found to belong to “los Casuals”.

The Boixos Nois, who have been banned from FC Barcelona’s stadium, have been the target of police operations in the past.

In 2018 police arrested 14 members for cocaine trafficking.