Hollywood actor Naomi Watts is to play Diana, Princess of Wales in a film examining the last two years of her life.
It will focus on a period prior to her death in August 1997 in which she had found "true personal happiness".
Caught In Flight is being made by director Oliver Hirschbiegel, best known for Downfall, a film about the final days of Adolf Hitler.
The film is being made by UK-based Ecosse Films.
British-born Watts, who emigrated to Australia in her teens, landed an Oscar nomination for her role in 21 Grams. She is also known for her roles in King Kong and Mulholland Drive as well as her TV ad for Thierry Mugler perfume.
"It is such an honour to be able to play this iconic role," Watts said. "Princess Diana was loved across the world and I look forward to rising to the challenge of playing her on screen."
Watts, who spent much of her childhood growing up in Wales, will begin work on the film later this year.
Filmmakers said the biopic "charts how finding true personal happiness for the first time allowed her to achieve her defining successes evolving into a major international campaigner and humanitarian".
A spokesman for the film was unable to say whether it would include her relationship with Dodi Fayed.
Actress Jessica Chastain had previously been in talks to take the role of Diana. Last year the late Princess was played by Lesley Harcourt in a US TV drama about the Duke and Duchess of Cambridge.
In the 2006 film The Queen she was played by a French lookalike.
The new film is based on a screenplay by playwright Stephen Jeffreys, who previously penned the script for the 2004 Johnny Depp film The Libertine.