Carabinieri Col. Maurizio Mezzavilla said the bomb was similar to the ones that exploded Thursday at the Chilean and Swiss embassies. An anarchist group with reported ties to Greek anarchists claimed responsibility for those blasts.
"Having been done in the same way, we can just hypothesize that there is the same hand behind it," Greek Ambassador Michalis Kambanis said at the embassy, although he added that he knew of no specific claim of responsibility.
Greek Foreign Ministry spokesman Gregoris Delavekouras said from Athens that no one was harmed in the latest incident, in part because heightened security measures had already been put in place.
"The embassy was evacuated and the staff assembled some distance away from the building, so that everyone could be accounted for," he told The Associated Press.
"There were already heightened security measures at the Greek and other embassies, so the procedure that had to be followed was clear."
Police, carabinieri and firefighters massed around the building Monday while the Greek Embassy staff lingered outside. The street, in the residential Parioli neighborhood, remained open to traffic.
Ambassador Kambanis said the package, hand addressed to the embassy, was discovered at about 10:30 a.m.
"We immediately informed the carabinieri who arrived here within three minutes," he said. "We (notified) the appropriate services and the bomb was neutralized."
There have been several other reports of suspicious packages in recent days that turned out to be false alarms. On Monday, police responded to suspicious packages at the embassies of Venezuela, Finland, Monaco and Denmark; all were false alarms.
"We don't take any chances in this situation," Danish Foreign Ministry spokesman Klavs A. Holm told the AP in Copenhagen. He said the embassy staff briefly evacuated the building and called authorities after a suspect package was found. It turned out to be a bottle of red wine.
"We have now resumed work," Holm added.
Police had told all embassies in the capital to be on alert after the package bombs on Thursday; Monday was the first day of business after the Christmas holiday. Some embassies chose to remain closed as a precaution: Sweden's Foreign Ministry said no packages had been found at its embassy in Rome but that it was closed Monday "for security measures."
An Italian group calling itself the Informal Anarchist Federation claimed responsibility for Thursday's blasts. News reports said that a claim found at one of the embassies cited the name of Lambros Fountas, a Greek anarchist who was killed in a shootout with police in March.
Interior Minister Roberto Maroni has said that investigators believe the anarchists who were responsible might have ties to Greek anarchists responsible for last month's letter bombings at Athens embassies.
On Nov. 2, suspected Greek anarchists sent 14 mail bombs to foreign embassies in Athens, as well as to Italian premier Silvio Berlusconi, French President Nicolas Sarkozy and German Chancellor Angela Merkel. Two of the devices exploded, causing no injuries.
Italian police chief Antonio Manganelli said Monday that to date there were no "material" links between the Athens and Rome bombings. But in comments to the ANSA news agency, Manganelli said contacts and synergies between anarchist groups of the two countries are constantly being investigated by joint Greek and Italian police operations.
A group called Conspiracy Nuclei of Fire claimed responsibility for the Greek blasts. It called on militants in Greece and other countries to step up their action, and Greek police noted last week that in the past acts of "solidarity" have been carried out between Greek and Italian militant groups.
But though the bombings were similar, Greek police have pointed out that the attacks there seemed not intended to cause injury - and none was caused. In contrast, the Italian attacks seemed intent on at least seriously wounding whoever opened the envelopes.
At least one of the devices contained an iron bolt that shot into the chest of the Chilean employee. That man also risked losing the sight in his eye; both he and the Swiss victim had serious injuries to their hands and arms, hospital officials said.
Associated Press reporters Paolo Santalucia, Alberto Mucci and Martino Villosio in Rome, Derek Gatopoulos in Athens, Jan M. Olsen in Copenhagen and Louise Nordstrom in Stockholm contributed to this report.