Caroline Flack posted a photo of her nipple on Instagram.

Caroline Flack (c) Instagram

Caroline Flack (c) Instagram

The 'X Factor' host was left red faced after she appeared to accidentally upload a snap of her new haircut with her nipple clearly visible in the bottom right corner.

She captioned the photo: "Summer party vibes ...Thank you for my hair and make up @gemflossy .... (sic)."

And although the 35-year-old presenter quickly realised her mistake and deleted the x-rated image, she later uploaded the same photograph but cropped it just enough so that her nipple could no longer be seen.

Appearing to acknowledge her rookie mistake, she wrote: "Bloody el.... Hair and make up by @gemflossy (sic)."

Meanwhile, Caroline - who previously dated One Direction heartthrob Harry Styles and music manager Jack Street - is currently preparing for the release of her first book, 'Storm In A C Cup'.

Revealing the news last month, she wrote: "HELLO LIFE! I've written a book about you.

"You've certainly been adventurous and I've made loads of stupid mistakes that have all ended up ok!!!!! Hooray. Available to pre- order now on AMAZON ... And out to read on October the 22nd... :) (sic)."