David Duchovny once thought he'd saved a man's life.

The actor - who stars in new movie 'The Joneses' alongside Demi Moore and Miley Cyrus - came across a stranger struggling for breath a couple of years ago and the quick-thinking star quickly administered the Heimlich manoeuvre.

He said: "I was in Vancouver shooting 'X-Files' and one night I went outside to walk my dog. I see a guy in a bathrobe, and as I got closer and I could tell he was choking.

"So I grabbed him and did my best Heimlich manoeuvre, like I'm really yanking on his diaphragm. Finally, he calmed down and I waited with him until an ambulance came."

However, it wasn't until a year after the incident that David realised he wasn't quite the superhero he thought he was.

The 49-year-old star said: "I was in a restaurant and he came up to me and said, 'Remember me. You gave me the Heimlich, but I was just having an anxiety attack.' I'm thinking, 'Thank God I didn't kill him.' Anyway, he bought me a drink."