An explosive device went off at the Swiss embassy in Athens on Tuesday, one of several locations targeted in similar attacks in the city.
Police spokesman Athanassios Kokalakis said an object was thrown into the Swiss embassy courtyard and a "deafening blast" was heard.
The Swiss foreign ministry confirmed that a package left at the Swiss embassy in Athens was the cause of a “problem”. A spokesman said the package burst into flames when it was unwrapped by local embassy staff but there was no explosion. No one was hurt. The Greek police have opened an inquiry.
A package also exploded at the Russian embassy in Athens, but there were no reports of injuries.
Several other packages were found and destroyed on Tuesday in the city and abroad.
German police disarmed a package bomb that was sent from Greece to German Chancellor Angela Merkel's office in Berlin. German Interior Minister Thomas de Maiziere said it was built in the same way and visually resembled the package that exploded at the Swiss embassy.
Also on Tuesday, two parcels were detonated in the cargo area of Athens International Airport. Police said they were addressed to the European Union's highest court in Luxembourg and the Europol law enforcement agency in the Netherlands.
Police detonated other parcel bombs destined for the German, Bulgarian and Chilean embassies.
No group claimed responsibility for Tuesday's attacks. Two local men have been charged with mailing bombs.
Greece has suspended international mail for 48 hours to carry out further checks.
swissinfo.ch and agencies