Demi Lovato. Picture: Demi Lovato/Instagram

Demi Lovato insists she doesn't "owe anybody" an explanation about her sexuality.

The 'Cool for the Summer' hitmaker has hit back after she was criticised on social media for refusing to reveal her sexuality.

She wrote on Twitter: "Just because I'm refuse to label myself for the sake of a headline doesn't mean I'm not going to stand up for what I believe in. If you're that curious about my sexuality, watch my documentary. But I don't owe anybody anything."

It comes after Demi insisted her sexuality is "irrelevant".

She said recently: "I just feel like everyone's always looking for a headline and they always want to be the one to break what my sexuality is. I feel like it's irrelevant to what my music is all about. I stand up for the things that I believe in and the things that I'm passionate about, but I like to keep my personal life as private as possible when it comes to dating and sexuality and all that stuff just because it has nothing to do with my music.

"Unfortunately, we live in a world where everyone is trying to get that soundbite and I am purposefully not giving the soundbite. Watch my documentary. I have a documentary coming out on October 12 and I answer a lot of questions in my documentary. Some about [sexuality]. Because if ever I want to talk about it, I want it to be on my own terms. I love who I love and I feel like I look at everybody who is outspoken about who they are as an inspiration and that's it."