ROME A suspect package was sent to an office of Italy's revenue collection office Equitalia and there were clashes outside other offices on Friday, amid growing public anger against tax authorities.
The package was delivered to an Equitalia office in Rome and was under investigation, police said. "There was a powder inside it but no detonator," an official said.
A letter bomb blew off part of the finger of Equitalia's director general in December, and a month later three explosive devices went off outside the agency's Naples office.
Prime Minister Mario Monti condemned the latest incident and issued a statement expressing solidarity with the agency's staff. He is due to meet Equitalia management on Thursday.
Equitalia, a publicly owned company responsible for collecting taxes and fines in Italy, has been the target of fierce criticism and occasionally violent protests as recession and a crackdown on tax evasion has hit small businesses hard.
The incidents have fuelled growing worries about the potential for violent unrest in Italy as the economic crisis begins to bite deeply.
A wave of highly publicized suicides, the latest on Friday when a plumber was reported to have burned himself to death in Sicily, has highlighted the human cost of the crisis on small business owners struggling to make ends meet.
Some have left suicide notes saying they could not afford to pay their taxes, arousing public sympathy following steep tax hikes imposed by the government last year to help shore up Italy's crumbling public finances.
Equitalia issued a statement rejecting blame for the suicides and said the "excessive superficiality" with which its name had been associated with the incidents risked fuelling tensions which could explode into violence.
In Naples, a group of students, union members and hard-left protesters threw bottles, eggs and firecrackers and blocked the street with rubbish containers after police moved in to break up a demonstration outside an Equitalia office in the city centre.
In a separate incident in the northern town of Melegnano, near Milan, two Equitalia inspectors were assaulted by a businessman during an inspection.
Last week, a 54-year-old businessman burst into an Equitalia office and held an official hostage at gunpoint for several hours before surrendering to police.
In a speech to a small business association on Thursday, Industry Minister Corrado Passera said he was increasingly concerned by threats to Italy's social cohesion as the crisis continues.
"The widespread social unease linked to the lack of work in Italy is broader than statistics tell us," he said.
(Additional reporting by Laura Viggiano in Naples and Sara Rossi in Milan; Writing by James Mackenzie; Editing by Andrew Roche)