London, July 26 - Paris Hilton's mother was shocked when she watched her daughter's documentary because the makers included scenes from the socialite's infamous sex tape. Kathy said it was 'hard' for them to see it.

The hotel heiress is the focus of 'Paris, Not France', a behind-the-scenes movie about the star's life that 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 Tuesday.

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 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,' Kathy told E! Online.