The guerrilla organization Conspiracy of the Cells of Fire and the Greek arm of the Informal Anarchist Federation (FAI) on Tuesday claimed responsibility for a letter bomb that was sent to an anti-terrorism prosecutor on Sunday and detonated without causing any injuries.

In a proclamation posted on the Internet, the group said it targeted Dimitris Mokkas at his Athens home in revenge for recent arrests over another bomb sent to a former head of the police’s counterterrorism service, Dimitris Horianopoulos.

The attack on Mokkas was part of “Project Phoenix 5 – Get the Judges,” which was launched in June with a bomb attack on the car of Korydallos Prison director Maria Stefi, the statement said.

It called on other groups to target judges in attacks ranging from assaults to “executions.”