ATHENS  After a season of bitter and widespread protests over austerity measures to address its financial crisis, Greece faced new turmoil on Wednesday as the authorities investigated an elaborate bomb plot in which relatively mild explosive devices were sent to embassies in Athens as well as to the leaders of Italy and Germany.

The authorities suspended the shipment of foreign-bound letters and small packages for 48 hours.

“Democracy will not be terrorized,” said Prime Minister George Papandreou, whose beleaguered administration is preparing for local elections on Sunday.