Demi Lovato takes aim at superfan for socialising with half-sister

Demi Lovato has warned a self-confessed celebrity hunter to stay away from her family after she was pictured with her half-sister Madison De La Garza.

The Heart Attack singer once posed for a selfie with superfan Sarah, who goes by the name Stalker Sarah and posts her star encounters on Instagram.com.

However, Demi launched into a rant at Sarah when she noticed the devotee had been posting multiple pictures with her 14-year-old actress half-sister Madison, warning her to stay away from her family.

"THIS IS MY 14 YEAR OLD BABY SISTER. You are a 20 year old fame LEECH. SHE IS NOT YOUR BABE... " the angry star wrote in a series of Instagram comments on Friday (08Apr16). "For anyone reading this: this girl has no regard for anyone's well being but her own. She completely takes advantage of people, even 14 year olds even though she's 20.

"My family is not afraid to press charges... I'm not your f**king 'girl.' If I was you (I) would not be asking for pictures. You STALK PEOPLE FOR A LIVING. We are NOT FRIENDS. Stay the f**k away from me and most importantly (my) family."

Demi has since deleted the comments, but only after they had been screen grabbed by members of the public.

This is not the first time Demi has let rip on social media over Desperate Housewives actress Madison. She once embarked on a tirade aimed at cyberbullies for poking fun at Madison, who suffers from scoliosis, back in 2014.

"For anyone telling me to 'chill'... The impact bullies have over the internet can lead people to suicide," she tweeted at the time. "I can handle the bulls**t. But do NOT f**k with my baby sister. I'm all for peace and spreading love UNTIL you go after a 12 YEAR OLD who did NOTHING to you... Physical disabilities are NOTHING to joke about. SEVERE SCOLIOSIS IS NOTHING TO MAKE FUN OF."

Madison and Demi, 23, share the same mother.