Callas was a US-born Greek soprano, and one of opera’s best-known singers.

In Maria, a blend of Jolie’s own voice and original recordings by Callas are used in the singing scenes.

The actress learnt to sing opera for the role, something she describes as “very physically demanding”.

Training took around seven months, she said.

“We started with regular singing classes and it was challenging in many ways, but when the opera classes began, what it requires with your breathwork and your body and just the force of what you push through yourself, it’s just a very different physicality.”

Jolie, whose previous film credits include Changeling, Maleficent, Salt, and Mr & Mrs Smith, said she hasn’t sung before, and was “actually quite shy about singing”.

“It was probably one of the areas in my life that I was hesitant,” she said.

But she indicated that it was also something she enjoyed.

“One of the greatest privileges of being an actor is you often are supported by a crew to try something and explore something you’ve never done and this certainly was most challenging,” she said.