It had been widely reported since early August that Spears was in the process of developing her biopic with producer Marc Platt and Wicked director Jon Chu, based on her recent memoir, The Woman In Me.

"Excited to share with my fans that I've been working on a secret project with #MarcPlatt," she wrote on social media at the time. "He's always made my favourite movies ... stay tuned."

Now, however, Spears has clarified that the secret project is not a biopic based on her life, but will instead be a musical story, according to reports by NME.

The Baby One More Time singer did not share more about the film's plot, but teased that she will be playing "an extremely intelligent character".

She also confirmed Jon Chu's involvement in the project.

The Woman In Me was a huge success upon release and has sold over 2.5 million copies in the US alone. The audiobook - narrated by Hollywood star Michelle Williams, with an introduction by Spears - is the fastest-selling in publisher Simon & Schuster's history.

The book contained a number of personal revelations including that she had an abortion while dating Justin Timberlake.