Spanish police said they had arrested 17 people in the northern city of Vitoria on Sunday after fascist supporters of former dictator Francisco Franco clashed with counter-protesters.
The rare violence comes as the European country marks the 50th anniversary of the general's death and grapples with the divisive legacy of his iron-fisted 1939-1975 rule.
The Falange -- an organisation that sees itself as the successor to defunct fascist movements that helped bring Franco to power -- rallied on national day in the northern Basque Country, which has a historic separatist movement, to defend "the unity of Spain".
Dozens of demonstrators gathered in a central square in Vitoria making fascist salutes and brandishing red and gold Spanish flags before hooded counter-protesters burst onto the scene, footage on social media showed.
Police charged at the rival protesters who were striking each other with poles, flags and chairs and hurling flares, according to the images.
Basque police said they had arrested 17 people suspected of public disorder after "radical groups" faced off, threw objects and burned waste containers.
Around 20 officers suffered "light bruises" and medical staff treated the injured protesters at the scene, the police added in a statement.
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