A parcel bomb was found at the Greek embassy in Rome on Monday, police said just days after two similar packages went off injuring two staffers at the Chilean and Swiss missions in the Italian capital.
The package was "similar to those that exploded last week in the Chilean and Swiss embassies," police spokesman Salvatore Cagnazzo told AFP.
"The mail worker at the embassy opened it but it didn't go off," he said, adding that the package was then de-activated by bomb disposal experts.
The explosive device was contained in a large padded yellow envelope with a CD case inside and was intended to detonate when opened.
Another police spokesman said earlier that two suspect packages found in the embassies of Monaco and Venezuela turned out to be false alarms.
Italian news reports said four other alerts in the embassies of Denmark, Morocco, Sweden and Ukraine also proved unfounded.
Greece's ambassador to Italy, Michael Cambanis, was quoted by La Repubblica daily on its website as saying that the parcel bomb had "arrived on Friday but no-one opened it because of the Christmas holidays."
Last Thursday two parcel bombs exploded at the Chilean and Swiss embassies here, injuring a Swiss mail worker and a Chilean diplomat.
Prosecutors on Monday said their "terrorism" inquiry for last week's bombs would now include the Greek embassy package.
Last week's blasts were claimed by an Italian anarchist group calling itself the Informal Federation of Anarchy (FAI). Investigators said they believed the claim was "reliable" and backed by "objective checks".
The FAI statement was signed by the "Lambros Fountas Cell" -- a reference to a Greek far-left activist killed in a shoot-out with police in March 2010.
A Greek police spokesman, Thanassis Kokkalakis, told AFP earlier there was no sign of involvement by Greek extremists but said the reference to the slain Greek militant showed a "measure of solidarity" between groups.
The FAI has claimed around 30 low-key attacks in Italy in recent years, starting with bombs set off in a rubbish bin outside the home in Bologna of then European Commission chief Romano Prodi in 2003.
The targets have been mainly the police and prison authorities and last week's bombs were believed to be the first attack claimed by the FAI to have injured someone.
Italian investigators have drawn parallels between last Thursday's bombs and a suspected anarchist far-left plot in Greece last month in which bombs were sent to foreign embassies in Athens and European government leaders.
Over a dozen packages containing explosives were sent in that plot, prompting Greece to suspend international mail for two days. At least four of the packages ignited or exploded, slightly injuring one person.