The director of a controversial Mexican film shortlisted for the Palme d'Or at the Cannes film festival has defended its explicit sexual content.
Actor Marcos Hernandez, actress Ana Mushkadiz and director Carlos Reygadas (right)
Batalla en el Cielo (Battle in Heaven) shows two obese child kidnappers having sex and a teenage girl performing a sex act on a middle-aged man.
Director Carlos Reygadas said: "Most people look more like them than the beautiful people you see in adverts."
The film is one of 21 movies up for the prestigious prize at the festival.
It was made with amateurs with no experience of acting in lead roles.
Reygadas's previous film Japon, which had a sex scene between a middle-aged man and an elderly woman, caused controversy at the 2002 Cannes festival.
At a Cannes press screening of the new film on Sunday, audience members booed and whistled.
In a graphic opening scene, the teenage girl, played by Ana Mushkadiz, performs a sex act on the man (Marco Hernandez).
The man is a chauffeur who along witrh his wife kidnaps the baby of a middle-class Mexico City family. But the kidnap is a botched job and the baby dies mysteriously.
The chauffeur is later shown having sex with his similarly overweight wife.
But at a press conference for the film, director Reygadas denied claims the scenes were pornographic and defended his choice of characters.
He said: "Porn aims to sexually excite the viewer. That's not what this is about.
"It was to create a sense that this goes much further than simple sex. There's a mystery behind it."
Hernandez - who plays the middle-aged man in the film - has worked with the director's father at Mexico's Ministry of Culture in Mexico for decades, while Mushkadiz - who plays the teenage girl - is an art designer, and was discovered at a casting.
Both newcomers said they were not sure if they would act again.
"I never wanted to be an actress," said Mushkadiz. "If nothing ever comes my way again, I don't care at all."