Matt Damon & Robert Downey Jr. join Christopher Nolan's upcoming epic Oppenheimer

According to inside sources, Hollywood stars Matt Damon and Robert Downey Jr. are the latest additions to Christopher Nolan's period piece Oppenheimer.

The two actors will be joining Cillian Murphy and Emily Blunt in Nolan's retelling of the life of the man often credited as the 'father of the atomic bomb' - J. Robert Oppenheimer.

The film, which is based on the 2005 Pulitzer Prize-winning book American Prometheus: The Triumph And Tragedy Of J Robert Oppenheimer, is slated to open on June 21st, 2023. Universal Pictures - the studio behind the film - has described it as an "epic thriller that thrusts audiences into the pulse-pounding paradox of the enigmatic man who must risk destroying the world in order to save it".

Both actors are yet to confirm the casting. IMDb has reported that Downey Jr. will play Lewis Strauss, former United States Secretary of Commerce, and Damon will take on the role of  Lt. Gen. Leslie Groves, the man who oversaw the Manhattan Project.

Cork-born Murphy, who has worked with the director on a number of projects already, will play Oppenheimer himself; while Blunt is set to play the physicist's wife, Katherine.

The film will mark the first collaboration between the 51-year-old director and Universal, after severing a nearly two-decade-long relationship with Warner Brothers. Nolan publicly criticised his old studio after they simultaneously released his latest film, Tenet, on both HBO Max and in cinemas without his consent.