A police statement said authorities seized three AK-47 assault rifles, three semi-automatic firearms, seven handguns, four grenades, 200 grams of TNT and 50 kilograms of ammonium nitrate explosives. The statement said police raided suspected insurgency strongholds in Athens, Piraeus and Crete.

Officials said the crackdown was targeting the Revolutionary Sect, which claimed responsibility for the killing of two people in late 2010. The group, which began operations in 2009, has been threatening to target police and journalists.

The security operation was launched in wake of a series of attacks on foreign embassies in November. The attacks, linked to a group called Conspiracy of Fire Nuclei, also targeted visiting European Union leaders.

So far, police reported seven arrests in the Dec. 4 operations. Three of the detainees were identified as members of Conspiracy of Fire Nuclei.

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