Angelina Jolie chartered a helicopter for Jack O'Connell to visit his sick friend

Jolie, who underwent a preventative double mastectomy last year and whose mother died of ovarian cancer in 2007, was on the set of the film in Australia and says she went out of her way to help him after he discovered a close friend of his had been diagnosed with liver cancer.

The 24-year-old actor: "I was feeling my worst, with the diet and the effects of preparation [for the film], and the only way I could possibly see him was if someone were to expedite the journey. And Angie arranged for a helicopter."

Jack admits "the whole film was very f**king brutal" and Angelina also organised a special meal to help him relax during filming.

He told DuJour magazine: "The same weekend, she organised some of my closest people around a table to have a meal with me. That exceeded the requirements of a director. It made me think how I had kicked the s**t out of myself for two months before starting the film, but all I wanted to do was be on set and repay the favour. That isn't a conventional actor-director relationship, so for her to make me feel like this was a two-way investment was so important."

Angelina, who has six children, Maddox, 13, Pax, 10, Zahara, nine, Shiloh, eight, and twins Knox and Vivienne, six, with husband Brad Pitt, admits it was difficult for her to ignore her instincts as a mother and push Jack and the other actors to their limits when they were portraying prisons of war.

She said: "All the boys had to starve - even the extras - and we'd have days when there were 200 young men just standing in the heat. The mother in me wanted to stop and put everyone under a tent and give them water and just call it a day. The other side of me had to do my job and push it forward."