Riot police are seen through a cloud of smoke during clashes with masked youths who occupied the Labour Center of Thessaloniki December 6, 2014. Greek police fired teargas to disperse protesters who hurled petrol bombs at police and set alight bank ATMs and garbage cans in towns around Greece on Saturday, during marches held on the anniversary of the 2008 police killing of a teenager. REUTERS/Alexandros Avramidis (GREECE - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY)