Police in Athens have safely destroyed a letter bomb sent to the French embassy, the 14th suspect device found in Greece this week.
They detonated the device, which had been concealed inside a book, in a controlled explosion.
A police source said the bomb seemed to have been posted along with others sent to foreign governments and embassies.
Two Greek men aged 22 and 24, who allegedly handled suspect parcels, have been charged with terrorist offences.
The wave of letter bombs sent to addresses in Greece and across Europe has led to Greece halting deliveries of overseas mail.
Small devices exploded at the Swiss and Russian embassies on Tuesday.
A courier employee was slightly injured when a bomb exploded in her hands.
The letter bombs apparently did not contain enough explosives to seriously harm any recipient, with police saying most burst into flames when they opened.
Analysts say the bombs are probably meant as a show of force by Greek leftist militants.
"All evidence shows this is a clear domestic case, with no connection with international terrorism," Greek Foreign Minister Dimitris Droutsas said on Wednesday.
"The evidence so far shows we are dealing with extreme left, anarchist groups."
The package sent to the French embassy was blown up outside a courier company. Reports say it was returned by the embassy.
It had been placed inside a hollowed-out book with the Orthodox archbishopric of Athens given as the return address.
Targets of earlier packages include French President Nicolas Sarkozy, German Chancellor Angela Merkel and Italian Prime Minister Silvio Berlusconi.
Panayotis Argyrou, 22, a chemistry student, and Gerassimos Tskalos, 24, were arrested on Monday allegedly in possession of one package addressed to President Sarkozy and another destined for the International Criminal Court in The Hague.
They had allegedly just posted off a parcel to the Dutch embassy in Athens.
Both men refused to recognise the court when they were charged with committing acts of terrorism, belonging to a criminal organisation, possession and use of bombs and explosives, as well as lesser offences including refusing to give their identities and fingerprints.
They have been remanded in custody.