Reese Witherspoon credits an elephant with being one of the best co-stars she's had.

The 'Water For Elephants' actress loved working alongside the animal because it was both dangerous and challenging.

She said: "It was one of the best experiences of my career. I worked with her for three months just training. I had to get into shape - I had no harness, no safety equipment, nothing.

"It was literally just me and the elephant and I had to climb onto her. She's 10 feet tall and over 900lbs, and it was this exercise in trust. It's a really Beautiful Thing where you learn to communicate with a creature non-verbally. She's the Big Star of the movie."

The film stars Reese as a circus performer whose horse dies, putting her act in jeopardy, until her husband - the circus ringmaster - buys her an elephant.

Reese, 34, added the elephant helps bring her character closer to Robert Pattinson's in the film, when they meet because of the creature.

She added: "Robert Pattinson's character comes in and he's a vet and we end up being very interested in each other. It's very romantic and beautiful."