A letter bomb addressed to Italian Prime Minister Silvio Berlusconi was the most recent discovery, following similar devices addressed to German Chancellor Angela Merkel and French President Nicolas Sarkozy, The New York Times reported. Other suspicious packages were addressed to the Athens embassies of Germany, Switzerland, Belgium, the Netherlands, Bulgaria, Chile, Mexico and Russia.
"Democracy will not be terrorized," Prime Minister George Papandreou said ahead of local elections Sunday. "The irresponsible and mindless acts of those who aim to undermine the efforts of the Greek people to put the country and the economy back on track will not succeed."
Government spokesman Giorgos Petalotis told reporters the bombs were most likely the work of domestic groups.
"It is quite clear that there is no link between the criminal activities of the past few days and international terrorist organizations such as al-Qaida," Petalotis said.
Two suspects have been arrested following the discovery of the parcel bombs, authorities said.
The Athens News Agency said the pair were taken into custody after allegedly bringing a suspicious package to a courier firm.
Five of the explosive packages turned up Tuesday and four other rigged parcels were found Monday.
A Greek official said at least one of the two men in custody was suspected of being linked to radical leftist organizations, the Times said.