"Oppenheimer" director Christopher Nolan has claimed that viewers have left the cinema "unable to speak" after seeing the eagerly anticipated film. 

The film, which sees Cork native Cillian Murphy star as the titular character, tells the story of American physicist J. Robert Oppenheimer and his role in the development of the atomic bomb during World War II.

A number of audiences have seen the film ahead of its scheduled release on July 21, prompting Nolan to speak about how the film affected them. 

"Some people leave the movie absolutely devastated. They can't speak," Nolan recently told WIRED.

"I mean, there's an element of fear that's there in the history and there in the underpinnings.

"But the love of the characters, the love of the relationships, is as strong as I've ever done."

Nolan went on to say that his new film is "an intense experience, because it's an intense story.

"I showed it to a filmmaker recently who said it's kind of a horror movie. I don't disagree."

He added: "But as I started to finish the film, I started to feel this color that's not in my other films, just darkness. It's there. The film fights against that."

When asked what he thought was going on in the real Oppenheimer's head, Nolan said: "I wrote this script in the first person. It's what I told Cillian [Murphy, who plays Oppenheimer]: You are the eyes of the audience. And he takes us there.

"The bulk of the storytelling, we don't go outside his experience. It's my best attempt to convey the answer to that question."

In "Oppenheimer," Murphy joins a star-studded cast, including Emily Blunt as Oppenheimer's wife Katherine, Florence Pugh as psychiatrist Jean Tatlock, and Matt Damon as General Leslie Groves Jr., the director of the Manhattan Project. 

It also features Robert Downey Jr. and Rami Malek

Based on the Pulitzer Prize-winning book "American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer" by Kai Bird, the film centers on the life of Oppenheimer as he works to develop the atomic bombs that would eventually be dropped on Hiroshima and Nagasaki in August 1945. 

You can watch the trailer for "Oppenheimer" here: