Around 100 people have been arrested in Spain after hooded demonstrators who participated in an anti-establishment rally looted shops and set fire to street furniture around Barcelona's central Plaza de Catalunya.
Núria Parlon, the interior minister for the Spanish region of Catalonia, said around 25 per cent of those arrested on Saturday night were minors. More than 30 fires were lit and 14 stores vandalised or looted in a part of town popular with tourists and weekend shoppers, she added.
Demonstrators were called in social media posts to a movement "against the system".
The posts also used the slogan "Institut Indignats", a translation of the movement "Lyceés Indignés" which was used to rally students who have protested in France in recent weeks.
In English, the phrases translate as "Indignant High School Student".
Social media videos show people trapped inside shops including department store El Corte Ingles after shutters were lowered to prevent looting.
Other posts showed hooded demonstrators dressed in black kicking in shop windows and making off with goods, in some cases encouraged by online viewers.
Barcelona Mayor Jaume Collboni said acts of vandalism in the city "will not go unpunished", including legal consequences for the guardians of any minors involved.