Cillian Murphy is playing the titular character in the much-anticipated World War II film (Picture: Universal Pictures)

Cillian Murphy is under ‘strict instructions’ not to spill the beans on the new Oppenheimer film, but it looks like he may have done just that.

The Irish actor, 47, is playing enigmatic scientist J. Robert Oppenheimer – who created the atomic bomb – in the hotly-anticipated Christopher Nolan film, set to hit cinemas on July 21.

The release comes the same day as Margot Robbie and Ryan Gosling are hitting the big screens for the pink-tastic Barbie epic.

So, in short, July has something for, er, everyone, whether you’re a war-movie fanatic or a Barbie super-fan. We love it.

Unlike the Barbie film – with its fabulous marketing and stream of teasers – Oppenheimer has been kept largely under wraps.

We do know that starring alongside the Peaky Blinders actor in the World War II epic will be a stellar lineup of Matt Damon, Emily Blunt, Florence Pugh, Sir Kenneth Branagh and Robert Downey Jr. Not bad going, that.

Florence Pugh is starring as psychiatrist Jean Tatlock  (Picture: Pascal Le Segretain/Getty Images)

Now, Cillian has let slip that he and 27-year-old Florence will, at one stage during the film, be bearing all with a bit of ‘prolonged full nudity,’ according to an interview with the The Guardian.

The Don’t Worry Darling star will be playing Oppenheimer’s ex-fiancé, with Emily Blunt taking up the role of his wife, Kitty.

While Florence and Cillian’s characters are said to be shown having sex, there are also – as the publication puts it – ‘complicated’ scenes with the Devil Wears Prada star.

Florence and Cillian are said to be getting ‘fully nude’ in the film (Picture: Universal)

Emily Blunt is also in the film, as Oppenheimer’s wife, Kitty (Picture: AP)

‘They put two actors in a room to see if there’s any spark, and have all the producers and director at a table watching,’ Cillian recalled.

‘I don’t know what metric they use, and it seems so outrageously silly, but sometimes you get a chemistry and nobody knows why.’

Oppenheimer has an R rating for ‘some sexuality, nudity, and language’, while in the UK it’s got a 15 certificate for ‘strong language and sex’.

Roll on July…

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R-rated.