Oliver Hirschbiegel, the German director of the planned biopic of the final years of Princess Diana, spoke of the warmth, humanity and empathy that Naomi Watts will bring to the role.
The movie, Caught in Flight, with a screenplay by Stephen Jeffreys, will be filmed in Britain this year by Hirschbiegel who directed Downfall, a film about Adolf Hitler's last days.
Watts, who most recently starred in J. Edgar, said: "It is such an honour to be able to play this iconic role – Princess Diana was loved across the world and I look forward to rising to the challenge of playing her on screen."
Watts was born in England and moved to Australia aged of when she was 14. She has starred in films including The Ring, Mulholland Drive, King Kong and J.Edgar.
Conspiracy theories, many put forward by Mohamed Al Fayed, former Harrods owner and father of Dodi Fayed, Diana's companion at the time, who was also killed in the crash on 31 August 1997, were demolished in the course of the much-delayed inquest, held in the high court between October 2007 and April 2008.
The jury decided the two had been unlawfully killed by a combination of the driving of their chauffeur, Henri Paul, and the driving of following vehicles. The inquest heard from 278 witnesses and the inquest was estimated to have cost £6.5m.
Publicity for the film speaks of its creating a compelling portrait of the last two years of Diana's life, charting how finding true happiness for the first time allowed her to achieve her defining success as an international campaigner and humanitarian.
Martyn Gregory, the journalist and film maker, whose book Diana: The Last Days was substantially borne out by the inquest verdict, said: "Let us hope it steers well clear of the conspiracy theories. If it is talking of true hapiness, it will need to show her relationship with the surgeon Hasnat Khan to whom she was much closer than she ever was with Dodi."
At the inquest Al Fayed dismissed the princess's friendship with Khan, saying: "You cannot say marry someone like that, lives in a council flat and has no money."
