Andrey Malanin, 54, was discovered by embassy staff on the floor of his bedroom this evening, Greek police confirmed.
Detectives confirmed they would draft in the police murder unit to examine the death because of Malanin’s high-profile status.
But they added it was unlikely he had been murdered and said he bore no signs of violent injury.
Nor was there any indication of a break-in.
Russian diplomats are on high alert following the assassination of its ambassador to Turkey, Andrei Karlov, by a policeman at an art gallery last month.