Packages have exploded at the Swiss and Chilean embassies in Rome, wounding two people. Police are checking all embassies in the Italian capital for potential problems.
Italian Foreign Minister Franco Frattini on Thursday condemned the embassy attacks as a "deplorable act of violence."
Police said a third suspicious package discovered at the Ukrainian embassy turned out to be a false alarm.
In the first incident, at the Swiss Embassy, a staff member who was opening the package sustained serious injuries to both his hands. The second blast occurred hours later at Chile's Embassy, also wounding one person.
The staffer at the Swiss Embassy was taken to a hospital as firefighters and police massed inside the embassy grounds to investigate the blast.
The explosions occurred amid growing concerns in Europe about possible holiday season attacks, after a recent suicide bombing in Stockholm and arrests this week in Britain of 12 terrorism suspects.
The Rome incidents are similar to a wave of parcel bombs found in Greece in early November that targeted Western leaders and embassies.
A Greek anarchist group claimed responsibility for sending more than a dozen parcel bombs, several of which exploded. One woman working at a private mail delivery company was slightly wounded when one of the packages exploded in her hands.
The embassy explosions in Rome followed a bomb scare Tuesday in the Italian capital's subway, after authorities found a suspicious package with wires and powder under a subway seat. Authorities later determined the device was a fake.