Christopher Nolan says his upcoming ‘Oppenheimer’ film is the ultimate blockbuster as it deals with the “survival of the world”.

The 52-year-old ‘Dark Knight’ director’s upcoming movie stars Cillian Murphy, 47, as “father of the atomic bomb” J Robert Oppenheimer, and the filmmaker said he has ever dealt with more important story.

He told Empire magazine: “The ultimate stakes of any big blockbuster is the survival of the world. And that’s what this story is.

“I know of no story with higher stakes than Oppenheimer’s story. That’s just the truth of it.

“It’s tricky using a word like entertainment when you’re talking about something so serious, but entertainment in movies takes many forms.

“This is such an involving, compelling tale that we had the privilege of telling.”

Christopher added one of his biggest challenges in making the film was shooting a recreation of the Trinity test of Oppenheimer’s bomb in the New Mexico desert without using any CGI.

He said: “I mean, I’ve done a lot of explosions in a lot of films. But there is something very unique and particular about being out in a desert in the middle of the night with a big cast, and really just doing some enormous explosions and capturing that.

“You couldn’t help but come back to this moment when they were doing this on the ultimate scale, that in the back of their minds they knew there was this possibility that they would set fire to the atmosphere.

“It was pretty amazing to engage in that kind of tension.”

‘Peaky Blinders’ actor Cillian has urged movie fans to see the film, out on 21 July, on the biggest screen they can find.

He told Empire: “I think it’s a truly essential cinematic experience. And I know that’s what I’m supposed to say – that’s the studio line.

“But you have to see this in the cinema on the biggest f****** screen possible. “There are moments in it that will blow people’s lids off.”