The statue of the young woman was found in a goat pen outside Athens, and Culture Ministry archaeologists soon declared it a fine 6th-century B.C. original.
But on Tuesday the ministry said a more thorough examination has determined it's a fraud.
Police seized the statue last week and arrested two suspected antiquities smugglers who allegedly were trying to sell it for (EURO)500,000 ($666,000).
A ministry official told The Associated Press the work is an imitation of a statue from that period. The official spoke on condition of anonymity in keeping with ministry policy.
It was unclear what would happen to the two men arrested pending trial on charges of antiquities looting.