Margot Robbie has revealed that she had to master an accent known as 'GenAm' for the forthcoming Barbie movie, saying there were 'very definite' elements to pick up.

Robbie, 32, stars in the new film as the titular doll alongside Ryan Gosling's Ken, with the pair joined by the likes of Will Ferrell, Michael Cera, Sex Education star Emma Mackey and Shang-Chi and the Legends of the Ten Rings actor Simu Liu.

A synopsis says: "After being expelled from Barbieland for being a less than perfect-looking doll, Barbie sets off for the human world to find true happiness."

Robbie, who is originally from Australia, not only had to dust off her American accent - having previously sported one for the likes of The Wolf of Wall Street - she had to use a very specific type of stateside drawl.

She revealed this to Vogue, adding that the doll’s voice changes as she struggles to get to grips with reality in the highly anticipated film.

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She told the magazine: "General American accent. It’s called GenAm.

“Everything is very definite. There’s no second thought. There’s no hesitation,” Robbie told the magazine."

During casting, director Greta Gerwig and Robbie also found themselves looking for an equally distinct 'Barbie energy' for their supporting cast of fellow dolls - saying Gal Gadot, who wasn't available, was the perfect example.

Robbie explained: “Gal Gadot is Barbie energy. Because Gal Gadot is so impossibly beautiful, but you don’t hate her for being that beautiful, because she’s so genuinely sincere, and she’s so enthusiastically kind, that it’s almost dorky.

"It’s like right before being a dork.”

In the end, they found their Barbies in the form of Issa Rae, Hari Nef, Emma Mackey, Dua Lipa, Sharon Rooney, Ana Cruz Kayne, Alexandra Shipp and Kate McKinnon, among others.

In another interview with Vogue last year, Gerwig admitted that taking on such an iconic character comes with 'a lot of baggage' from the 'nostalgic connections' it has.

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She said: "But with that come a lot of exciting ways to attack it. People generally hear ‘Barbie’ and think, ‘I know what that movie is going to be,’ and then they hear that Greta Gerwig is writing and directing it, and they’re like, ‘Oh, well, maybe I don’t..."

She also told Dua Lipa's At Your Service podcast the whole experience was 'terrifying', explaining: "I think there's something about starting from that place where it's like, ‘Well, anything is possible!’

"It felt like vertigo starting to write it. Like, where do you even begin? What would be the story? I think it was that feeling I had that it would be really interesting terror. Usually, that's where the best stuff is. When you're like, ‘I am terrified of that.’ Anything where you're like, ‘This could be a career-ender,’ then you're like, ‘OK, I probably should do it.’”

Barbie hits cinemas on 21 July.