A police spokesman said the parcel to the justice minister held "a small quantity of explosives" and was detonated in a controlled explosion Wednesday, the Financial Times reported.
The package was delivered by courier, with the sender named as the "Independent Lawyers' Initiative," officials said. Aides to Justice Minister Haris Kastanides said they thought the package was suspicious and called police.
The police spokesman said no one so far has claimed responsibility.
Nine suspected members of the militant Conspiracy of the Cells of Fire went to trial in January, accused of sending 14 parcel bombs last November to mostly foreign embassies in Athens.
Besides sending a parcel bomb to German Chancellor Angela Merkel, similar packages were sent by courier to Italian Prime Minister Silvio Berlusconi, the international court of justice at The Hague, Netherlands, and Europol, the European criminal intelligence agency, the Times said.