Angelina Jolie is very secretive.

But in a new interview with BBC News, the Hollywood star spoke candidly about her experience working on set with her older sons, saying they saw "the pain" she usually hides. from them.

The actress is a star in a new biopictitled Maria, about the opera singer Maria Callas.

Two of Jolie's six children with ex-husband Brad Pitt, Maddox and Pax, took roles as production assistants on the film.

"The character (Callas) is in a lot of pain and of course they've seen me go through a lot of things, but they hadn't experienced me expressing a lot of the pain that a parent usually does. hiding from a child," she said. said.

"So they were there to witness some of that, but then we'd wake up or they'd give me cups of tea."

Jolie said it was a "new way" to figure out how to be honest with her children about her feelings, "in an even bigger way".

Written by Peaky Blinders creator Steven Knight, the film focuses on Callas' last years, in the 1970s, when she lived in Paris.

With Jolie taking part in acting quite often in recent years, the film has given her something of a comeback statement and could lead to an Oscar nomination for best actress.

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

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

The actress learned to sing opera for the role, which she says is "very physically demanding".

Training took about seven months, she said.

"We started with regular singing classes and it was challenging in many ways, but when the opera classes started, what it requires with your breath work and your body and just the strength of what you push through yourself, no it's just a very different physique. "

Jolie, whose previous film credits include Changeling, Maleficent, Salt, and Mr & Mrs Smith, said she had never sung before, and was "really shy about singing".

"It's probably one of the areas in my life that I've been lazy about," she said.

But she said it was something she also enjoyed.

"One of the biggest perks of being an actor is that you often have the support of a crew to try something and explore something you've never done before and this was definitely a big challenge, " she said.

Jolie's sons Maddox, 23, and Pax, 21, have worked on several productions with her before, including her film Without Blood.

The two joined her at the premiere of Maria in New York in September, along with their younger sister Zahara.

Jolie filed for divorce from Pitt in September 2016. The couple were involved in a custody battle that led to Pitt being granted joint custody in 2021.

The Hollywood stars also share daughters Shiloh and Vivienne, and another son Knox.

On the set of the film, both Maddox and Pax were "very busy", director Pablo Larraín said. "They were great professionals," he said.

Jolie said that during filming, Pax recorded much of her singing routine "so he was with me in my terrible days," she laughed.

"It's always good for your kids to watch your mom not do something easy, but swear and fight and fail and you have to try again," she said.

"So that's an important and beautiful thing."

Maria is the third in a series of films about high-profile, complex women from Larraín, following his films about Jacqueline Kennedy and Princess Diana.

The film has received mixed reviews, although critics have generally praised his lead performance.

"Jolie is absolutely stunning as Maria Callas, embodying her with grace and intent," said AwardsWatch's Sophia Ciminello. "She doesn't disappear into the role, she transcends it."

Time's Stephanie Zacharek was less keen performed, however, saying that Jolie "plays her subject so incredibly cool and very uncertain, but she doesn't capture any of her imperial charisma".

Known as La Divina, "The Divine One", Maria Callas started singing at 14 years old.

One of her most famous performances was as Tosca, in Covent Garden, in 1964.

But a vocal decline, possibly caused by a dramatic weight loss, brought her career to a premature end.

She spent her last years living largely alone, and died of a heart attack at the age of 53.

Larraín said he hoped his film honored Callas' desire to popularize the art form.

"If this film takes opera attention from one to a hundred to a million, it will be a success," he said.

"I don't know if there is an art form as strong as opera," Jolie said.

"The way it connects with the soul and the body, so really it's for everyone."

Maria is released in UK cinemas on January 10.