Nicole Kidman has stepped up to defend her upcoming Grace Kelly movie following criticism from the late star's royal relatives, insisting her portrayal will be "respectful".

The Bewitched star plays the actress-turned-real-life princess in her new movie Grace of Monaco, but the film has come under fire from Kelly's children, Prince Albert Of Monaco, and his sisters, Princess Caroline and Princess Stephanie, who recently branded the project "pointlessly glamorized," "inaccurate" and "pure fiction".

Kidman has now spoken out about the controversy, insisting she found the part "daunting" at first, but tried to make sure she honored the Hollywood legend's memory.

Speaking at a London screening of her new film Stoker, she told reporters of her Grace Kelly role, "I wanted to be respectful of her, her story and her essence so hopefully that will all come through. It's exciting but at first it was daunting. At the same time I had studied her and felt a kind of tenderness towards her."

Screen legend Kelly became Princess Grace of Monaco when she wed Prince Rainier III in 1956. She died at the age of 52 after a car accident in 1985.

Grace of Monaco is due for release in 2014.

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