The film marks a departure from Ryan's traditional roles

Ryan stars in In The Cut, an erotic thriller written and directed by The Piano director Jane Campion, based on the book by Susanna Moore.

She plays New York academic Frannie Avery who becomes involved with a detective (Mark Ruffalo) investigating a murder in her neighbourhood.

It is being talked about by critics because it marks such a departure for Ryan - often typecast as an all-American blue-eyed blonde.

She is best known for her appearances in popular box office comedies such as When Harry Met Sally and Sleepless in Seattle.

But her role in In The Cut led to one critic describing the performance as "the most astounding change of image by a leading Hollywood actress in recent times".

Ryan, 41, appears naked, and the film is said to be sexually explicit and violent.

The film, co-starring Jennifer Jason Leigh and Kevin Bacon, is expected to open in Britain in late November. The Toronto festival runs from 4 to 13 September.