An envelope containing bullets and a letter was found Thursday at the Greek Embassy in Spain, just a day after an identical package was sent to the Greek Consulate in Barcelona, officials said.
Spanish authorities opened the letter and found small caliber bullets and the letter, according to Greece's Foreign Ministry and Julia Livaditi, an embassy spokeswoman.
Livaditi would not say what the letter said, and Spain's Interior Ministry and national police declined comment on its content and their investigation.
But an official with the Greek Embassy in Spain said the letter had a message in Spanish saying: "Be careful how you treat people who have been arrested." The official spoke on condition of anonymity because he was not authorized to discuss the matters related to the investigation.
The letter arrived at the embassy with no return address, and numerous stamps, the official said. Greek embassies around the world have been advised to be cautions when receiving such letters following a spate of parcel bombings at embassies in Athens in November, the official said.
Last month, letter bombs were sent to three embassies in Rome by Italian anarchists in solidarity with jailed Greek anarchists.