Police on Friday announced that a proclamation was included in the letter bomb sent to Korydallos prison and neutralised by bomb disposal experts on Thursday.

They announced that the manila envelope containing the bomb also contained a small roll of paper wrapped in insulating tape, which proved to be a proclamation claiming responsibility for the attack signed by the Italian organisation "Informal Anarchist Federation - International Network".

The proclamation was written in Italian and said the letter bomb was sent to show solidarity with the jailed members of the Greek terror group "Conspiracy of Cells of Fire" and imprisoned 'comrades' in Chile, Switzerland and Germany.