London, Sep 2 (IANS): Actress Naomi Watts says she was worried about the reaction of Prince William and Harry to "Diana", a biopic on their mother, the late Princess Diana.

The 44-year-old actress, who stars as the late Princess of Wales in the film, was concerned that Diana's children may not approve of the film, which is based on the romantic life that the late royal shared with heart surgeon Hasnat Khan, reports contactmusic.com.

"That was another reason I was really holding back because you always wonder how they [her boys] feel about it. That's always the big thing in my mind, you know, would they approve," InStyle magazine quoted Watts as saying.

But she has clarified that no part of the movie is offensive.

"I know for certain there's nothing offensive in this movie. It's really the retelling of her life. The boys are in it for one scene. Their presence is there, but it is the focusing on that love story," she added.

To justify her character as the princess, the actress was fixated on one of the Princess' interviews, which originally broadcast in 1995, to the point where she was watching it even while working out.

"I ran the Martin Bashir TV interview so often that it got to the point where I was watching it on my iPhone while I was out jogging. I had five minutes of her walk, five minutes of her wave, five minutes of her laugh that I'd watch again and again," Watts said.