The Australian actress made the allegations about the British comedy star in her memoir, Rebel Rising, which was released in the US yesterday.

A representative for Baron Cohen describes her claims as "demonstrably false", in a statement given to the PA news agency.

Wilson, 44, starred alongside Baron Cohen, 52, in the 2016 spy action comedy Grimsby, known as The Brothers Grimsby in the US, playing his on-screen girlfriend.

Best known for films including Bridesmaids, Jojo Rabbit and the Pitch Perfect series, Wilson says she is not aiming to cancel the Ali G and Borat star, but wants to share her alleged experiences as "the more women talk about things like this, hopefully the less it happens".

Wilson claims she felt that every time she talked to Baron Cohen during filming in South Africa, "he'd mention that he wanted me to go naked in a future scene", which she says was in "no way essential" to the plot.

She accuses him of giving "gross directions" and says it appeared as if he "wanted me to look and feel awful", allegedly making her change into smaller clothes "where you could see as much cellulite as possible".

Wilson also details a particular alleged incident on set, claiming she was "lured" out of her trailer into an unfurnished concrete room with a mattress on the floor, with the only people in the room being Baron Cohen "and his mates".

She alleges that Baron Cohen pulled down his trousers as his friends recorded on their phones, telling her: "Okay, now I want you to stick your finger up my ass", for a scene that he said would be in the film.

Wilson, who says she was "scared", claims there was no director or film crew around, and adds: "It's my opinion that Sacha Baron Cohen gets off on making people feel uncomfortable."

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A representative for Baron Cohen told the PA news agency: "While we appreciate the importance of speaking out, these demonstrably false claims are directly contradicted by extensive detailed evidence, including contemporaneous documents, film footage, and eyewitness accounts from those present before, during and after the production of The Brothers Grimsby."

Baron Cohen's wife Isla Fisher also appears in the film, alongside Mark Strong, Penelope Cruz, Ricky Tomlinson and Johnny Vegas.

Wilson says she did not want to be labelled a "troublemaker" at the time, but shared a version of her claim on social media during the #MeToo movement in 2017, without naming Baron Cohen.

Elsewhere in her memoir, Wilson describes other comedy actors such as Ben Stiller as a "total gentleman" on Night At The Museum: Secret Of The Tomb, and says Will Ferrell "could not have been lovelier" when producing Bachelorette.

She also lists "lovely" encounters with Seth Rogen, Jason Segel, Bob Saget, Robin Williams and Garry Shandling.

Sky News has contacted representatives for Baron Cohen for comment.