Hardcore Lazio supporters attacked fans of Real Sociedad on Wednesday night in Rome ahead of their Europa League match, leaving nine Spanish people injured, one seriously, Italian media reports said.

Around 80 Lazio "ultras" attacked around 70 supporters of the Spanish club who were visiting the Italian capital for Thursday's match at the Olympic Stadium, the AGI news agency said.

Dressed in black with their faces covered, and wielding firecrackers and smoke bombs, the attackers beat up and stabbed the Spanish fans gathered in the Monti district, in the heart of Rome's historic centre.

Chairs and tables were also thrown at the Spanish fans, according to the newspaper Il Corriere della Sera.

Police have seized a small arsenal of weapons, including knives and hammers, from the Lazio ultras, and made several arrests, the reports said.