U.S. actor George Clooney plays a New Age hippie soldier trained for psychic, peaceful combat in a comedy set during the war in Iraq.

The Men Who Stare at Goats is based on a book by Jon Ronson about a secret unit created by the U.S. army in 1979 which, the author said, believed troops could become invisible, walk through walls and kill goats just by staring at them.

Ewan McGregor plays a reporter who stumbles across a member of the unit as he prepares to enter Iraq, and he and Clooney's character Lyn Cassady go on an ill-fated journey that sees them kidnapped, shot at and hit by a roadside bomb.

Jeff Bridges is a long-haired, drug-taking leader of the New Earth Army, and Kevin Spacey completes the line-up as a rival to Cassady who ends up turning the unit into a lucrative private enterprise operating in Iraq during the war.

What we love about this film and what's so fun about it is that there's a tremendous amount of it that's true, Clooney told reporters in Venice, where the movie premieres on Tuesday.

As funny as it is, it's some of the dumbest parts of the film that are the true parts, so that's what made us laugh the most, added the 48-year-old Hollywood star.

NOT FILM ABOUT WAR

Although set in Iraq in recent times, the war is only an incidental backdrop to a comedy which drew loud laughter at a press screening.

We thought that this wasn't an Iraq war film, said Clooney. We thought of it as a comedy about some crazy ideas that went on that started at the end of the Vietnam war and carried on through not that long ago and maybe still carry on.

Director Grant Heslov added: It really is more about when you take the idea of trying to do something wonderful, something beautiful, something different, and along the way it gets perverted.

Times aren't great, they're not easy, there's a war going on, there's a financial crisis ... and yet in spite of all this you still need guys who believe in something and that's what I loved about Ewan's character.

Clooney laughed off questions about his personal life, including one journalist who asked him if he could imagine falling in love and marrying a man.

Grant and I are actually announcing our wedding while we are here, he joked. I don't quite know how to answer that question, but I can read your mind again and I know what you're thinking.

Another man in the audience announced that he was gay and removed his shirt and trousers as he spoke.

Iraq