A Greek anarchist guerrilla group claimed responsibility on Monday for a planned parcel bomb attack against a judge at a courthouse in the northern city of Thessaloniki this month, the third such incident since December.

Police last week confiscated the parcel, which was sent to a senior judge and contained explosive material, before it exploded.

In a statement uploaded on Athens Indymedia website on Monday, the previously unknown anarchist group “Armed Response” said that it was behind the attack against authorities, accusing judges of “inhumane” rulings and of cooperating with the conservative government.

The group warned of more attacks against prosecutors, police and judges, including the judge who was meant to receive the parcel.

Greece has a history of political violence.

Small bomb and arson attacks against politicians, judges and businesses, among other targets, became more frequent just before and during the country’s 2009-2018 debt crisis but had decreased in the past five years.

The country has seen a resurgence in recent months, after the conservative government was re-elected last year, and police are further investigating the incidents.

On Feb. 3, a bomb went off outside Greece’s labour ministry in central Athens causing no injuries but damaging the building. In December, another explosive device, planted at the headquarters of the riot police unit (MAT), was defused by police.