The often controversial director, who won an Oscar for gun control movie "Bowling for Columbine" and scored the highest-grossing documentary of all-time with anti-war film "Fahrenheit 9/11," was hosting a symposium at the Academy of Motion Picture Arts and Sciences featuring nominees for best documentary features and short subjects.

"We've been living in a time where people have been lied to a lot," Moore told Reuters. "People are tired of it and they want the truth, and documentaries represent the truth."

Throughout his career Moore has been criticized by some for being too one-sided in films that range from 1989's "Roger & Me" about laid off auto workers to 2007's healthcare analysis "Sicko" and two years later, "Capitalism: A Love Story."

But he has been praised just as widely by many admirers, and Moore offered his usual candor and wit when questioning each of this year's Oscar nominees about their work. He joked about moving down the "line of misery" when discussing films on a range of subjects from acid attacks to the tsunami in Japan.

Feature film documentaries nominated for this year's Oscars include, "Hell and Back Again" by Danfung Dennis, "If a Tree Falls: A Story of the Earth Liberation Front" by Marshall Curry and Sam Cullman, "Pina" by Wim Wenders, "Undefeated" by TJ Martin and Dan Lindsay, and "Paradise Lost 3: Purgatory" by Joe Berlinger and Bruce Sinofsky.

The third in a trilogy of movies about a grisly Arkansas murder case known as the West Memphis Three, "Paradise Lost 3" looks at how the film series helped secure the release of three men imprisoned for a crime they claim they didn't commit.

"Even affecting one person is really wonderful," Berlinger told Reuters. "And I think documentaries have a unique power to change the events that they're covering."

"Hell and Back Again" producer Mike Lerner's film sheds light on the plight of war veterans more likely to succumb to suicide than to enemy fire.

"Undoubtedly it has a massive impact," he said about non-fiction film. "Knowledge is good and information is good. And people empathizing and understanding has got to be a good thing for the world."

But not all of this year's Oscar docs deal with crime or war. Wenders' "Pina" looks at the life of German dance choreographer and ballet director Pina Bausch using 3D, which is highly unusual for a documentary.

Inspirational movie "Undefeated" covers a team of high school football players from a poor neighborhood in Memphis, Tennessee who are struggling to make something of themselves.

Among short films, documentary "Incident in New Baghdad" centers on a 2007 Apache helicopter attack that killed 12 civilians, including a boy, leaving his sister severely wounded.

"I think it just totally unmasked what war is; the mistakes that get made, the way things escalate, (and) really the total mercilessness of it." said director James Spione. "But the second thing that disturbed me was the treatment of the American media of it as this political football."

The other nominees for their short films were "God is the Bigger Elvis" by Rebecca Cammisa and Julie Anderson, "The Tsunami and the Cherry Blossom" by Lucy Walker, "Saving Face" by Daniel Junge and Sharmeen Obaid-Chinoy, and "The Barber of Birmingham: Foot Soldier of the Civil Rights Movement" by Robin Fryday and Gail Dolgin who succumbed last year to breast cancer.

(Reporting by Jordan Riefe; Editing by Bob Tourtellotte)

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