Eight parcel bombs have been found and neutralised by police in Greece.
The packages were found at an Athens postal office and were addressed to European Union finance officials and European businesses.
No one was hurt.
The find comes after a book concealing explosives was intercepted by German authorities on 15 March before reaching its intended recipient - German finance minister Wolfgang Schaeuble.
That attack was claimed by Greek militant group Conspiracy Cells of Fire, which has become prominent since the economic crisis began in their country.
On 16 March, a letter bomb addressed to the Paris-based office of the International Monetary Fund exploded, injuring an administrative assistant.
Greek authorities think Conspiracy of Fire Cells is behind this attack too, although the group has not claimed responsibility for this attack.
Conspiracy of Fire Cells started its history with arson but turned to bombings in 2009 and police blame them for more than 150 crimes since then.