Kristen Stewart believes the spirit of Princess Diana gave her a "sign-off" for her performance in 'Spencer'.

The 31-year-old actress portrays the late royal - who died in a car accident in 1997 - in the upcoming biography and she admitted she experienced some "spooky, spiritual feelings" while shooting the film, which focuses on a three-day period over the 1991 festive season when Diana was staying at the Sandringham estate.

"Asked whether she had ever had a paranormal encounter, she said: “No. But I felt some spooky, spiritual feelings making this movie. Even if I was just fantasising. I felt like there were moments where I kind of got the sign-off.”

And Kristen admitted there were times when she "forgot" Diana was dead and it "destroyed" her every time she remembered the princess was no longer alive.

She told the LA Times newspaper: “[Diana] felt so alive to me when I was making this movie, even if it’s all between the ears and it was just a fantasy of mine. But there were moments where my body and mind would forget she was dead.

“It was … a fight to keep her alive every day, and so remembering that she was dead was just absolutely lacerating. It just destroyed me constantly. And that itself felt spiritual … there were times where I was like, ‘Oh, God,’ almost like she was, you know, trying to break through.

"It was weird. And amazing. I’ve never felt anything like it in my life.”

Kristen recently spoke of her admiration for Diana,insisting she is unlike many public figures of the past.

She said: “We haven’t had many of those people throughout history. Diana stands out just as a sparkly house on fire.”