Ryan Reynolds had panic attacks on the set of his new movie 'Buried'.

The 'Proposal' actor - who plays Paul, a US contractor in Iraq who is buried alive in a coffin with just a mobile phone and a lighter - admits he had moments of "utter panic" when he was shooting the project because of the enclosed space he had to be in.

He said: "Claustrophobic is a primal fear that exists within everybody.

"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 the Canadian star's fear during the movie - which was directed by Rodrigo Cortes - he claims there was little he could do in way of preparation for the role.

He told Shock Till You Drop: "Prep-wise there's not a lot you can do. 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.' "