Demi Lovato is reportedly just friends with One Direction's Niall Horan as she's still besotted with her ex-boyfriend.

The singer-and-actress was spotted on a dinner date with the One Direction star on Friday night. Despite the cosy nature of their meal, sources close to the X Factor US judge say it was completely innocent.

"Demi just isn't interested in Niall that way at all. She sees him as nothing but a friend," insiders told Perez Hilton. "In fact, she's still head over heels in love with Wilmer Valderrama and it's only a matter of time before they get back together. They aren't officially dating but they definitely aren't seeing other people."

Demi's been hanging out with the One Direction boys during their recent trip to America to perform at the MTV Video Music Awards (VMAs).

As the latest judge on the US version of the show the British boy band found fame on, Demi has some common ground with the youngsters already. She has previously spoken about her excitement to be on the programme.

"The new season of X Factor is going to be amazing," she told TMZ. "With tons of drama between the contestants, which I haven't seen but I'm dying to see."