Naomi Watts Terrified By Lady Diana Role for Upcoming Film

Actress Naomi Watts has revealed that she is "terrified" about playing the legendary Princess Diana in an upcoming film and also admitted that she initially wanted to turn down the role.

The English actress, who launched her acting career in Australia, will play the royal icon and late mother to Princes William and Harry in the upcoming film "Caught in Flight." It explores the final two years of Princess Diana's life, particularly her reported affair with heart surgeon Dr. Hasnat Khan, according to Mail Online.

"I'm looking forward to it, but am absolutely terrified. It's going to be a tough one. It's a big beast to take on. I just try to do my best," Watts said at an event at The Orangery in London's Holland Park on Wednesday night.

"The filmmakers came to me and it's a good script. It's very scary, and I kind of wanted to say 'no' but I couldn't. Now I'm doing all the research and there is so much to read ... There is so much information and one story is different from the next so it's hard to gauge what was the truth," she added.

The Academy award-nominated actress is renowned for her roles in successful Hollywood films including "The Ring" and "King Kong," and many fans expect that the 43-year-old will do a great job portraying Princess Diana, who was tragically killed in a 1997 car accident.

"She's a very inspiring woman and it's impressive how she changed the whole gearing of the traditions of the royal family and opened it up and brought a warmth to," she explained. "I just hope we make a good film and people can learn something new about her that's interesting."

The film, which is directed by Oliver Hirschbiegel, is due for release in 2013 and production is set to begin later this year.