Rome is on high alert after packages exploded in the Swiss and Chilean embassies.
The parcel bombs injured two people who opened them.
Suspicion has fallen on anarchists from an eco-terrorism movement.
Back in October, an explosive device was found near the embassy wall with a note calling for the freedom of three anarchists extradited from Italy to Switzerland on suspicion of planning an attack on an IBM facility.
These latest incidents are raising fears of more attacks over the holidays. Of particular concern are the mass gatherings in St. Peter's square over Christmas.