Action man Jeremy Renner feared he would vomit on his Mission: Impossible - Ghost Protocol co-star Tom Cruise as they filmed stunt scenes while hanging out of a window in the world's tallest building in the United Arab Emirates.

The stars shot pivotal scenes in Dubai's Burj Khalifa building and one sequence sees Renner almost falling out of a window as he reaches out to save Cruise.

But The Town actor admits he felt so sick to his stomach, he had to warn Cruise to beware.

Renner says, "It doesn't feel very safe when you have just a tiny little (stunt) wire on your pant. You hang out (of the window) and you're about a mile up in the air. I almost vomited. I told him, 'Tom, I might throw something down on you.'...

"Everything looked like a little Lego land down below. And I figured, if I fell, I could at least make a few phone calls on my way down. It was so far!"