Rio police were examining the corpse and scene but could not say whether it was that of the envoy, 59-year-old Kyriakos Amiridis.
"The information that we can confirm right now is that we have found a car in (the district of) Nova Iguacu with a body and it is being investigated," a source in the homicide squad told AFP.
The source would not say whether the license plate of the car was from the rental the ambassador was using, nor when DNA results on the body would be back.
Amiridis had been on vacation with his family in Rio de Janeiro's northern Nova Iguacu area since December 21.
He was due to fly back to Brasilia on January 9, a Greek embassy official told AFP.
But he went missing on Monday night, after going out of the apartment they were renting and taking the car, according to Brazilian media. His Brazilian wife formally declared him missing on Wednesday.
The Greek foreign ministry had earlier issued a statement saying that after Amiridis was declared missing, "the full mobilization of all the competent Brazilian authorities was requested."
Amiridis was named ambassador this year. He had previously served as Greece's consul general in Rio from 2001 to 2004.
He served as Greece's ambassador to Libya from 2012 to 2016.
He is married and has a daughter, according to the embassy in Brasilia.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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