ROME -- Italian authorities moved Thursday to step up police protection for thousands of people and offices considered potential targets of violence triggered by anger over Italy's economic crisis.

The decision by Interior Minister Anna Maria Cancellieri to assign 18,000 law enforcement officers to security detail was prompted by the shooting two weeks ago of a top nuclear industry executive and recent threats and acts of aggression directed at offices of Equitalia, the state tax-collection agency.

Hostility is running so high against Equitalia that Prime Minister Mario Monti paid a visit Thursday to the tax agency’s office and assured employees of his unconditional support.

To deal with the threat of further violence, Cancellieri convened a meeting of a national security committee, where she said the latest events demonstrated that "it is necessary to maintain a high level of attention and vigilance," said a statement from the Interior Ministry.

Roberto Adinolfi, 53, a senior executive of the nuclear engineering company Ansaldo Nucleare, was shot in the leg May 7 by a gunman on a scooter in Genoa.

A group calling itself the FAI, or Informal Anarchist Federation, claimed responsibility a few days later in a letter sent to the Milan daily Corriere della Sera. It accused Adinolfi of being "one of the sorcerers of the atomic industry."