(updates with press conference)

By Bob Tourtellotte

CANNES, France, May 24 (Reuters) - The men of "Ocean's Thirteen" -- Brad Pitt, George Clooney and their crew -- have turned their Hollywood hype machine into a campaign to raise money for Darfur refugees.

"Ocean's Thirteen" debuts at the Cannes Film Festival on Thursday and the movie starring Clooney and Pitt as suave con men who rob casinos is as easy-going as the blockbusters preceding it -- "Ocean's Eleven" and "Ocean's Twelve".

"We've known each other too long -- we know each other's families -- and it's just an instantaneous rhythm that sets in" when working on the movies, Pitt told Reuters.

"And, of course, the movies themselves have never been high drama ... (fun) is the point of it."

The cast gave tongue-in-cheek responses to dispel any impression that "Ocean's" aspired to the art house cinema that was Cannes's trademark.

"This script, for instance, I think may go down in the history books as one of the great screenplays of all time," Clooney said. "This film is basically a cry for peace."

When asked about a scene he plays with Oprah Winfrey towards the end of the movie, actor Andy Garcia replied: "I had to sleep with Oprah in order to get on to the show."

The first movie delighted audiences and raked in $450 million at box offices worldwide. While some fans and critics were disappointed with "Twelve," it nevertheless reaped a sizeable $363 million.

"Ocean's Thirteen" sticks closely to the formula of the first two: a lot of laughs, some silly gags and a big heist. But there is a twist: the conmen are not in it for the money.

FROM HOLLYWOOD TO DARFUR

The charity of Clooney, Pitt, Matt Damon, Don Cheadle, and producer Jerry Weintraub does not stop on the movie screen.

They also came to the world's largest film festival to raise money and awareness for refugees in the Darfur region of Sudan.

"We're not politicians. We're not able to make decisions. We're not able to do anything except bring attention to something, and that's the thing we can do," Clooney said.

"Kids are dying from diarrhoea ... that just shouldn't be in this day and age, and it's that kind of thing that needs to be changed. Enough is enough," Pitt added.

The United Nations says some 200,000 people have died and more than 2 million have fled their homes since the conflict in Darfur flared in 2003 when rebels took up arms against the government.

Four "Ocean's Thirteen" cast members -- Clooney, Pitt, Cheadle and Damon -- and Weintraub launched the Not On Our Watch Foundation to raise money and draw attention to the refugees.

Earlier this week, they raised $10 million at a Cannes party, and in June they head to Los Angeles, Las Vegas and Chicago for similar charity events.

Clooney took issue with anyone doubting his motives.

"At what point does anyone think anyone of us needs more publicity?" Clooney said. "I'm not going to defend what I think is doing the right thing ... we are doing it because we all think we would be criminal if we didn't take it a step further." (Additional reporting by Mike Collett-White) (Please visit our Cannes site, including a link to our blogs, on http://uk.reuters.com/news/globalcoverage/cannesFestival)

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