Britney Spears felt "very uncomfortable" on The X Factor US panel.

The international songstress joined last year's panel alongside Simon Cowell, Demi Lovato and L.A. Reid, but departed after just one season.

Kelly Rowland and Paulina Rubio now sit alongside Cowell and Lovato after Spears and long-serving judge Reid left at the end of last series.

In an interview on The Ellen DeGeneres Show, music mogul Cowell revealed how he ended up choosing Spears for the hit TV talent show.

He explained: "I think if I'm being honest with you, Ellen, there was a time I think everyone was trying to up themselves in terms of who could find the biggest known star to be on a panel.

"And in terms of a pop singer? Jennifer Lopez and the other one on The Voice... I can't remember. Blondie. Christina. And we said, 'We'll take Britney'. She was fine, but I think she found it very uncomfortable."

Cowell also agreed when the host added she wasn't a big talker.

He exclaimed: "I didn't realise that! I kind of booked someone who couldn't talk, which is a bit of a problem when you want someone to judge.

"She wasn't comfortable being negative, she didn't like it when the contestants spoke back to her, so she was just uncomfortable. I liked her. So we decided to change it this year."