Greece's Culture Ministry has launched an investigation after the release of a short film showing people having sex at the ancient Acropolis in Athens.
The 36-minute movie, titled Departhenon, was released online on December 21 but only came to the attention of authorities this week.
The Culture Ministry said it had not given permission for the film shoot at the World Heritage site.
The section at the Acropolis shows two men having sex while standing in a circle formed by other actors. Visitors to the ancient site can be seen nearby.
"The archaeological site is not suitable for any kind of activism or other activity which would cause offence and displays disrespect for the monument," the ministry said in a statement.
Departhenon contains several explicit scenes involving actors whose faces are not shown.
The film, which opens to the soundtrack of Stevie Wonder’s funky 1973 hit Higher Ground, also sees the actors painting their bodies and wearing masks as they embark on their “erotic adventures”.
The makers of the movie, who remained anonymous, described it as "artwork that is also a political action".
An accompanying caption describes how the actors wanted to set the sex scene in “a space which is aggressively charged with heteronormal and nationalistic values”.
Spyros Bibilas, the president of the Greek Actors' Association, described the movie as shameful.
"You can't do everything in the name of activism. In fact, I don't consider this to be activism," he told TV network Antenna.
"As a Greek, I feel ashamed."