VENICE (REUTERS).- Up-and-coming Irish actor Michael Fassbender plays a sex addict in "Shame," a movie by British video artist Steve McQueen that is vying for the top prize at the Venice film festival. It is the second lead role for Fassbender in a competition movie at this year's festival after his portrayal of psychoanalyst Carl Jung in David Cronenberg's "A Dangerous Method."

In Shame, the German-born Fassbender is Brandon, a handsome, 30-something executive living in New York whose only distraction from work is seducing women, masturbating at home or in the office and looking for sex on the Internet.

The tightly controlled rhythm of his life begins to fall apart when his needy, dysfunctional sister Sissy, played by Carey Mulligan, arrives for an unannounced visit.

Her presence, and her craving for Brandon's attention, disrupt his lonely existence even further, and his only way out seems to be wandering the streets at night in search of new sexual adventures.

Fassbender, whose portrayal of Brandon was warmly applauded after a press screening Sunday, said taking part in the film's graphic sex scenes was not easy.

"Yes (it was) uncomfortable doing the sex scenes, you just have to jump and turn really," he said.

"The most important thing I guess is that everybody involved feels as comfortable as they can. And then just go for it so you don't have to do too many takes."

McQueen, whose debut film was the widely acclaimed "Hunger" about the last months of Irish Republican Army activist Bobby Sands in Belfast's Maze prison, said he saw similarities between the two films.

Hunger also starred Fassbender in the lead role.

"Clearly Hunger was a political film but Shame is also political. That one was about a prison in northern Ireland, this one it's about how someone's freedom can actually imprison them and they need an addiction in order to numb a pain, how our lives have been changed sexually by the Internet," he said.

"I love Brandon, he's trying and it's difficult. He's not so far away from most of us at the end of the day. He is not a bad person, I think the character is not at all repulsive, maybe unfamiliar but extremely recognisable."

The title Shame was chosen after interviews with sex addicts and their experiences in preparation for the film.

"The word shame came cropping up in those interviews," McQueen said.

His career began with film-related projects, he quickly branched out to include sculpture and still photography, and his work has been displayed at the Biennale of Art in Venice.

McQueen said he saw no big differences between his artworks and his feature films.

"There are no barriers between the two. Of course in one you're going to have a bit more narrative and the other less so, but the process is the same, it's work."

Asked why Mulligan, who was in Australia to shoot Baz Luhrmann's "Great Gatsby," had not come to Venice to present his movie, McQueen replied: "It's out of order. She should be here.

"I am very upset about that, actually. I don't know Baz Luhrmann, whatever ... I wouldn't do to him what he did to me."

(Reporting By Silvia Aloisi, editing by Mike Collett-White)

© Thomson Reuters 2011. All rights reserved.