The revelation in Whitney, which was made with the co-operation of the singer's family, comes late in the film by Oscar-winning Scottish director Kevin Macdonald, which was premiered Thursday at the Cannes film festival.

Houston's assistant, Mary Jones, who Whitney called "Aunt Mary", discovered her face down in a Beverly Hills bath the night she died, told the filmmakers that she was abused as a child and was later unable to come to terms with her sexuality.

It may help to shine a new light on the singer's descent into drug addiction and early death at 48 in 2012.

Houston's destructive relationship with the rapper Bobby Brown is also tackled in the documentary, by the maker of One Day in September about Black September hostage taking at the 1972 Munich Olympics.

Brown tells the film that drugs had nothing to do with Houston's death, although the coroner said it was a contributing factor.

Dee Dee Warwick was the younger sister of the soul legend Dionne Warwick. She also struggled with drug addiction and died aged 63 in 2008.

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Macdonald told AFP that he always wondered what was at the root of Houston's unhappiness.

"For a long time I had looked at her on screen and thought there's something about this woman that feels so uncomfortable. 

"She doesn't enjoy her own body in some way. She's very beautiful but not sexual, she feels uncomfortable in her skin. I began to wonder whether it was abuse."

"Then somebody told me that they had spoken to Whitney about it and that's what she had said had happened to her, and she felt that that was the origins of her unhappiness."

Whitney Houston's soaring gospel voice made her one of the biggest pop stars of the 1990s, selling 170 million albums and starring in the smash hit Hollywood love story, The Bodyguard

Whitney is the second film about the tragic singer in less than a year. Another British documentary maker, Nick Broomfield, released his Whitney: Can I Be Me late last year.