Three explosive devices blew up outside the Naples offices of Equitalia, a state agency that collects overdue taxes and fines, breaking windows but injuring no one on Monday night, a police official told Reuters.
Police said no group had claimed responsibility for the attack on the building on Corso Meridionale near Naples central rail station.
Equitalia, whose offices have been attacked before, is deeply unpopular among many Italians who accuse it of using strongarm tactics to collect taxes.
Italy's technocrat government says it wants to increase Equitalia's powers as part of a war on tax evasion that robs the exchequer of an estimated 120 billion euros (99.12 billion pounds) a year.
Separately, members of right wing association Roma Nord said they hung dummies outside Equitalia offices in Rome overnight to protest against the agency's methods, Italian news agency ANSA reported.
Equitalia's Naples offices were hit by a similar explosion in December.
Two letter bombs were also sent to Equitalia's offices in Rome in December. One was intercepted but the other blew off part of a finger of the agency's director general. An anarchist group said it carried out those attacks.
(Reporting By Laura Viggiano and Catherine Hornby; Editing by Andrew Heavens)