NEW : Police chief says only Greek mail parcel contained an explosive . USA : ` ` The new system has changed '' An anarchist group claims responsibility for the bombings at the Swiss , Chilean embassies . A Greek official denies an Italian minister 's claim that the bombings originated in Greece .
NEW : Police chief says only Greek Embassy parcel contained an explosive . Chief : `` The alarm system has worked '' An anarchist group claims responsibility for the bombings at the Swiss , Chilean embassies . A Greek official disputes an Italian minister 's claim that the bombs originated in Greece .