Naomi Watts plays Princess Diana: First image released

The first image of Naomi Watts playing Diana, Princess of Wales, has been released by film company Ecosse.

The British-born actress is starring in a film that portrays the last two years of Princess Diana's life.

Principal photography started this week. The film is due out next year.

Speaking from the set, Watts said: "I'm excited and honoured to be playing the role of a truly remarkable woman, who had such a positive and profound impact in so many ways."

Since being announced in February, the film has changed its name from Caught in Flight to the simpler Diana.

Directed by Oliver Hirschbiegel of Downfall fame, it is believed to explore the princess's relationship with the heart surgeon Hasnat Khan.

The pair had a discreet romantic affair that began in 1995 and ended a few months before her death in August 1997.

Ecosse said the biopic "charts how finding true personal happiness allowed her to achieve her defining successes, as she evolved into a major international campaigner and humanitarian".

Dr Khan will be played by Naveen Andrews, from The Buddha of Suburbia and Lost, with other cast members including Douglas Hodge and Juliet Stevenson.

It is rumoured the film will also touch upon the princess's relationship with Dodi Al Fayed, and her death following a Paris car crash.

Ecosse directors Robert Bernstein and Douglas Rae have moved to quash any criticism of the film, saying that "everyone's aim [was] to produce a truly insightful and compassionate study of Diana's later years".

Watts rose to fame in Australian soap opera Home and Away before enjoying big-screen success in King Kong, 21 Grams and Mulholland Drive.

Aged 43, she is six years older than Diana was when she died.