Britney Spears is looking for a new artist with "spark and spunk".

The superstar singer has joined the judging panel of the US version of The X Factor, where she sits alongside Demi Lovato, Simon Cowell and L.A. Reid.

Britney is taking her role seriously and strives to give every wannabe artist a proper chance to shine.

"It's been fun, it's been a lot of fun," she said.

"I'm looking for someone who shows spark and spunk [and that] they're meant to do what they're doing. I think I'm a fair judge. Sometimes it's kind of hard because I know what they've been through and being so young it's such a delicate situation when they're that young. You just have to use constructive criticism and be there for them and show them support."

Britney has been cited as the hardest member of the panel to impress by some. She insists that crown belongs to one of the men though, as she always tries to be kind.

"I don't think I'm the toughest judge at all," she is quoted as saying by Access Hollywood. "I definitely think Simon would have to be the toughest judge."

The panel have been travelling across America looking for talent, with Demi underwhelmed by what was on offer in Kansas City. They later visited San Francisco, which she told an XFactorUSA.com crew member she was happier with.

The 19-year-old singer added she sometimes worries about the effect her opinions will have on the hopefuls.

"My judging style is very honest, sometimes I worry that I'm too harsh I really just say it like it is. I'm not considered the nice judge or the mean judge," she said.

"It's really hard for me to smile if they're performing and they're horrible. I have to be super, super honest and sometimes I feel bad about it."