Actor/comedian Ricky Gervais has been left in excruciating pain after aggravating an existing shoulder condition during a play session with his cat.

The Office star has been suffering from adhesive capsulitis, which causes pain and stiffness in the shoulder, and he recently managed to irritate the condition.

He tells U.S. TV host David Letterman, "I was playing with my cat the other day and I'm just teasing it and it jumped and it frightened me and I went back and suddenly I was on the floor crying in agony.

"My girlfriend's going, 'Are you OK?' The cat is going, 'I didn't, I didn't do anything'."