Ryan Reynolds - who plays Paul, a US contractor in Iraq who is buried alive - admits he had moments of “utter panic” when he shooting his new movie Buried.

“Claustrophobic is a primal fear that exists within everybody,” Reynolds said. “For me I was enclosed in there and had moments of utter panic that were soothed in various ways. One woman was playing all the roles when we were shooting. I had a microphone close to my chest and she could hear my panic attack starting ‘cause she could hear my heart accelerating. There were times when I couldn’t get out of the coffin with any ease so I just had to stay in there with 50-60 pounds of wood on your chest pressing down so you start to have moments of panic.”

Despite Ryan’s fear during the Rodrigo Cortes-directed movie, he claims there was little he could do to get ready for the role.

“Prep-wise there’s not a lot you can do,” he told Shock Till You Drop. “This guy’s experiencing something extraordinary. I couldn’t actually imagine what that was like, so for me most of the prep happened moments before. I wanted to get inside and see if the shoe fit, I jumped in the coffin, ‘Yep, it fits, let’s go.’”

Buried debuts in limited release today. The movie will then open everywhere on October 8.