Bradley Cooper: 'Hangover II hardest shoot'

Bradley Cooper has revealed that filming The Hangover Part II was one of the most difficult projects he has ever done.

Speaking to Entertainment Weekly, the cast of the comedy sequel revealed that production on the movie in Thailand was a challenge, something which director Todd Phillips had previously asserted.

"It was the hardest shoot I've ever done for sure. Nothing ever even came close to it," Cooper explained.

Co-star Ed Helms revealed that many of the cast and crew had suffered food poisoning, which had in turn made the atmosphere even tougher.

He said: "It does something to your mind when you get that sick. You go to a scared, dark place."

Zach Galifianakis, meanwhile, admitted that he had been reluctant to come onboard the project, after the surprise success of The Hangover in 2009.

"I was a little bit apprehensive. I was just of the mindset, 'Oh, let's leave well enough alone'," he added.

Last month, the artist that created Mike Tyson's distinctive facial tattoo accused the producers of The Hangover Part II of copyright infringement and sought to delay the release of the film.

The Hangover Part II is scheduled for release on May 26.

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Watch the trailer for The Hangover Part II below: