New behind-the-scenes stills from Angelina Jolie's Unbroken have been released, Digital Spy said.

The film, directed by Jolie, will feature Skins star Jack O'Connell as Olympian and war hero Louis "Louie" Zamperini, who was taken prisoner by Japanese forces during World War II.

Unbroken's principal actors have been on strict diets for months, as they play depleted characters who have been stranded at sea for 47 days, after surviving a near-fatal plane crash.

Domhnall Gleeson, who has the role of war hero Russell Allen Phillips, recently spoke of his dramatic weight loss, saying that it makes it "more authentic".

The film also stars Tron's Garret Hedlund and Die Hard 5's Jai Courtney, and is scheduled to be released in the UK on Christmas Day, 2014.

It has been adapted for the screen, from Laura Hillenbrand's book, by the Coen brothers, William Nicholson and Richard LaGravenese.

Unbroken will mark Jolie's third directorial outing, after the 2007 documentary A Place in Time and 2011's In the Land of Blood and Honey.