Washington, July 25 : American socialite Paris Hilton's mother has revealed that she was shocked to view a screening of her daughter's documentary, as filmmakers included scenes from the hotel heiress' infamous sex tape.

`The Simple Life' star is the focus of `Paris Not France', a behind-the-scenes movie about the star's life, which was made three years ago.

The picture premiered at the Cannes Film Festival in France earlier this year, and will make its TV debut in America on July 28.

Hilton's mother Kathy watched the documentary at a preview screening, but she wasn't prepared to see footage of her eldest daughter engaging in sex acts with ex-lover Rick Salomon - in extracts from the notorious 2003 video One Night In Paris.

"I didn't know (the sex tape) was going to be in it. It's very tough. I can't believe they kept that part in there. I thought they kept that part out. It's very hard for us to watch," Contactmusic quoted her as having told E! Online. (ANI)