Steven Spielberg says his animals worked "miracles" on the set of War Horse.

More than 150 equine performers featured in the Oscar-nominated movie.

Veteran horse trainer Bobby Lovgren, who grew up in an equestrian family in South Africa, oversaw the horses on the film.

"Bobby and his team literally performed miracles with the horses on this film," the director said.

"I wanted it to feel like the horses were performing their parts as much as (actors) Emily Watson or Peter Mullan, and that is what happened.

"There were times during production when the horses reacted in ways I had never imagined a horse could react.

"You just sit back and thank your lucky stars that these horses are so cognisant that they are able to give everything to a moment."

War Horse is up for six awards at next month's ceremony, including best film.