It is too early to tell who may have planted the devices. However the incident bore strong resemblance, including size and packaging, to a series of recent bombings in Rome and an earlier string of similar attacks in Greece. Anarchists groups claimed credit for those attacks.
Sources told ABC News that the devices that exploded in Rome were addressed to the Swiss, Chilean and Greek embassies and bore correct postage. The packages listed the sender as a cultural association, for example the Cultural Association Italy Greece, or the Cultural Association Italy Andes. They also had a return address of via Mameli 44, 00177 Rom, a nonexistent address.
The packages in Italy were described by authorities as cushioned yellow envelopes containing an interior soft envelope with a zipper that held a pyrotechnical mixture as well as metal balls for shrapnel. The devices were powered by a battery and activated when the packages were opened.
These characteristics were similar to those of devices that had exploded in Greece recently as well.
In November, book bombs were mailed to government offices and heads of state across Europe. One was found at the Chancellor's office in Berlin. Several were found in Athen's Greece where one small firebomb ignited, injuring a shipping clerk and leading police to the discovery of three more devices as well as the arrest of two bombers.
The incendiary bomb in a hollowed out book went off in the hands of a shipping clerk at Swift Mail in Athens on Nov. 1 as she was preparing to ship it to a Mexican Embassy.
According to a police report from Greece, the explosion at Swift Mail triggered a rapid police response that led to the arrest of two young men about two blocks away from the shipping firm as they were entering a metro station clad in bullet proof vests and wearing wigs. Two nine millimeter Glock pistols and five full magazines were recovered.
According to the report in addition to the bomb that exploded the men admitted to attempting to mail other bombs and appeared to have been carrying one in a plastic bag when approached by police.
The recovered bombs were addressed to Nicolas Sarkozy, a Belgian embassy and a Dutch Embassy. The one to Sarkozy was also recovered at Swift Mail. The one to the Beligan Embassy was recovered at a second shipping firm -- ACS. And the one in their possession was addressed to a Dutch Embassy.