NEW YORK - Demi Lovato has said she feels "lucky to be alive" and has hit out at tabloids in a series of tweets about her health and recovery on Friday.

The US singer was taken to hospital in July for an apparent drug overdose and has undergone rehab treatment since.

In a series of posts, Lovato confirmed she was now sober and urged fans not to trust what they read in the media.

"If I feel like the world needs to know something, I will tell them MYSELF," she said in one tweet.

"Any 'source' out there that is willing to talk and sell stories to blogs and tabloids about my life isn't actually a part of my life," another post said.

"Someday I'll tell the world what exactly happened, why it happened and what my life is like today but until I'm ready to share that with people please stop prying..." she added, asking for more "space and time" to heal.

Lovato was a child actor on Barney and Friends, but found wider fame on the Disney Channel as a teenager.

She starred in its hugely popular Camp Rock film series and then launched a successful solo music career. The 26-year-old has released six studio albums and has also appeared as a judge on the US version of the X Factor. Lovato has been open about her struggles with mental health and addiction throughout her career.

In a 2017 documentary, she revealed the depths of her struggles with substance abuse during her teen years. In June, Lovato released a song titled Sober in which she revealed she had broken her six years of sobriety.

A month later, US news website TMZ broke the news of an apparently near-fatal opiate overdose by the star.

The singer has been largely absent from social media and the public eye since the incident, and the full details around it remain unclear.

The six posts on Friday are the first time she has referenced the matter in depth since a now-deleted Instagram post thanking fans in August.

"I'm so blessed I get to take this time to be with family, relax, work on my mind, body and soul and come back when I'm ready," she said on one post on Friday.