Singer Taylor Swift is keeping tight-lipped about reports she will play Joni Mitchell on the big screen because the movie has yet to receive the greenlight.

The country star has long been rumoured to be portraying the folk icon in a film adaptation of Sheila Weller's book Girls Like Us, which chronicles the lives of singer/songwriters Mitchell, Carly Simon and Carole King.

Swift admits she would love to tackle the role, but she's reluctant to discuss her link until bosses at Sony Pictures make it official.

Chatting about the casting, she tells Time magazine, "That's actually not confirmed. I wish I could say it's confirmed! But the thing about movies that I've learned is - I've been reading scripts for five years, and you just don't know what ones are going to get greenlit and which ones aren't, so I can't talk about it unless it's the real thing...

"I would love to sign on to do a movie if it was the right role and if it was the right script, because I would be taking time away from music to tell a big grand story, and spend all of my time and pouring all of my emotions into being someone else. So for me to do that, it would have to be a story worth telling."

Swift has only dabbled in acting so far - she had a small role in the 2010 romantic comedy Valentine's Day and voiced a character in animated children's movie The Lorax.