Action icon Arnold Schwarzenegger has revealed that he almost died on the sets of The 6th Day and True Lies.

He told the stories in a Reddit Ask Me Anything (AMA), an interview held directly with users of the popular website that the likes of Bill Murray and President Barrack Obama have previously taken part in.

"On True Lies, you probably remember the horse scene," said the Terminator star. "There was a shot where the horse had to stop at the edge of a building.

"They built a little ramp to give the horse longer to stop. But when they were measuring the new distance from the ramp to the camera, they dropped the arm of the camera on the horse's nose, and it went crazy, spinning and rearing.

"There was no rail, and the ramp was only 4 feet wide. I realised it was a bad situation and I slid off the horse right away and a stunt man grabbed me. That one was really scary. If the horse stepped a foot the wrong way, we would have fallen 90 feet to a cement floor. These stories are why I will always love stunt people."

The former governor of California took part in the AMA to promote his children's charity After-School All-Stars.

"On The 6th Day, there was a scene where I hide underwater behind embryos. I did a rehearsal with goggles and everything went fine. But when we actually shot, I couldn't see because the water was milky," Schwarzenegger said.

"So I ran out of air and went to the top and realized I didn't know where to get out. I was trapped. Then a hand grabbed me and pulled me out. It was my stunt double, Billy Lucas. He'd been watching from below with a tank and goggles and realised I was in big, big trouble."

Arnie, who returned to starring roles in 2013's The Last Stand is set to reprise his role as Trench in Sly Stallone's third Expendables movie before reprising his most famous role in an upcoming Terminator reboot.

You can read the full AMA here.