Demi Lovato has opened up on life as an X Factor USA judge, admitting that Simon Cowell's nagging is getting little wearisome.

The singer and actress was announced as a new judge for the TV talent show alongside Britney Spears earlier this year.

Speaking to Access Hollywood, she lamented Cowell's nagging nature but revealed that she's happy to give it back. She said:

"Simon's great, but he nags on me so much that I don't know if I can take it any longer. I'm a brat. I'm annoying. But I give it back to him."

Lovato also spoke of fellow judge Britney Spears, adding that she is "charming" but also a little intimidating due to her star status. She said:

"She's really sweet, just really loving and charming, but she's intimating because she's such a big star."