“There are also connections with more traditional Juventus fan groups and other far-right militants.”
The operation, which focused on a hangar in a small airport in Pavia, in the northwest of the country, uncovered a rocket launcher that had until recently used by Qatar’s armed forces.
The missile, which did not carry an explosive charge, was manufactured in France in 1980, Euronews reported.
The haul of Nazi material included a large shield with a swastika, a sign reading "Adolf Hitler Platz" and other wartime insignia.
Italian media said the operation targeted an "ultras" fan group of Serie A team Juventus FC.
The ultras are an organised group of football supporters who are known to have links to fascist groups.