Sylvester Stallone has revealed he broke his neck while filming new movie, The Expendables.

The 63-year-old actor was engaged in a “vicious” fight scene with former wrestling star Stone Cold Steve Austin when the injury occurred.

Sly told FHM he was forced to undergo an emergency operation to have a metal plate inserted in his neck.

"Actually, my fight with Stone Cold Steve Austin was so vicious that I ended up getting a hairline fracture in my neck,” Sylvester said.

“I'm not joking. I haven't told anyone this, but I had to have a very serious operation afterwards.

"I now have a metal plate in my neck."

The Expendables promises to be a heavyweight spectacle, with Arnold Schwarzenegger, Bruce Willis and Jason Statham also starring.

The movie is due to be released worldwide this summer.