No injuries were caused by Wednesday's controlled detonation outside the ministry building near central Athens.
The booby-trapped package was delivered by courier and had been addressed to the minister's office, with the sender listed as an "independent initiative of lawyers," said police spokesman Athanasios Kokalakis. Staff at the ministry deemed the package suspicious and called the police.
The attempted attack was similar to a spate of letter bombs in November during which 14 letter bombs were sent mostly to embassies in the Greek capital.
One of the booby-trapped packages made it to German Chancellor Angela Merkel's office in Berlin before being destroyed, while another addressed to Italian Premier Silvio Berlusconi caught fire aboard a courier flight that had landed at Italy's Bologna airport.
"We have a similar package to those sent in November," Kokalakis said of Wednesday's bomb, adding that the letter was believed to have contained a small amount of explosives.
A militant anarchist group, Conspiracy Nuclei of Fire, has claimed responsibility for the November bombings, which caused no injuries. Nine suspected members of the group, mostly in their early 20s, went on trial in January over the attacks. Four others are being tried in absentia, and the process is expected to take several months.
The group has vowed to target the judicial system, threatening to blow up judges involved in the trial. It also has claimed responsibility for a powerful bomb that exploded outside an Athens courthouse on Dec. 30, causing extensive damage to the building and cars parked nearby, but no injuries.
In internet postings, Conspiracy called for solidarity from anarchist groups around the world - sparking copycat parcel bomb attacks on embassies in Rome in December. Those attacks injured two people and prompted Greek and Italian authorities to investigate links between extremists in both countries.
Last week, envelopes containing bullets were sent to the Greek Embassy in Madrid and the Greek consulate in Barcelona.
Armed radical groups have been active in Greece for decades, mostly carrying out targeted assassinations against high-profile targets or small-scale bombings of diplomatic vehicles, car dealerships and banks. Most bombings are preceded by warning calls or are carried out late at night, and few cause any injuries.
But after several years of relative calm, Greece has seen a resurgence of militant groups, particularly after riots sparked by the fatal police shooting of a teenager in Athens in December 2008. Conspiracy Nuclei of Fire, which initially appeared before the riots, at first carried out small scale firebombings.
Other groups have been more deadly.
The Sect of Revolutionaries, which emerged in the wake of the riots, claimed responsibility for killing an anti-terrorism police officer in June 2009, and a journalist last July.