Angelina Jolie: My children Maddox and Pax saw my pain on the set of Maria

Callas was a US-born Greek soprano and one of the most famous opera singers.

Maria’s singing scenes use a mix of Jolie’s own voice and Callas’ original recordings.

The actress studied opera for the role, which she describes as “very physically demanding”.

The training took about seven months, he said.

“We started with regular singing lessons, and it was challenging in many ways, but when you start opera lessons, what it requires of your breathing and your body and the power you just push yourself, it’s just a very different physicality.”

Jolie, whose previous film credits include Changeling, Maleficent, Salt and Mr & Mrs Smith, said she had never sung before and was “too embarrassed to actually sing”.

“That was probably one of the areas where I was hesitant,” he said.

But he said it was something he liked too.

“One of the great privileges of being an actor is that you’re often supported by the crew to try something and explore something you’ve never done, and that was certainly the most challenging,” he said.