Actress-turned-director Angelina Jolie has been wearing a special necklace on the set of her new prisoner-of-war movie Unbroken after receiving the gift from the film's real-life subject.

The Wanted star has started work on the movie adaptation of Olympian Louis Zamperini's survival story, and she has a lucky charm to help her make all the right decisions.

Zamperini, who was captured by the Japanese during World War Two, struck up a close friendship with Jolie while she was developing the project, which is now shooting in Australia, and he has shown his support for the Hollywood beauty by giving her a gold pendant in the shape of a running shoe - a nod to his days as an athlete at the 1936 Berlin Olympics.

He tells People magazine, "Angelina is a human dynamo, and I know she will tell this story in the right way."

Jolie admits tackling Zamperini's life story has been a little daunting, but she's proud to be in charge of the project, which is based on Laura Hillenbrand's biography.

She says, "Like all readers of Laura's book and all people who love and admire Louis, I am a fan. It will be hard to make a film worthy of this great man. I am deeply honoured to have the chance."

British newcomer Jack O'Connell will portray Zamperini in the film, while Domhnall Gleeson has been cast as war hero Russel Allen Phillips.

Zamperini became a prisoner of war in 1943 when his U.S. Air Force plane crashed down in the Pacific and he was captured by Japanese soldiers behind enemy lines after spending over a month at sea without food or water.