Demi Lovato has returned with a big anthemic single, Sorry Not Sorry, after taking a year-long break from music.

Sorry Not Sorry, which debuted on 11 July, is said to be the lead single from Lovato's forthcoming sixth studio album, which is expected for release later in 2017. Produced by Zaire Koalo, Warren "Oak" Felder and Trevor Brown, the r'n'b-tinged track features the 24-year-old hitting back at the haters.

Clearly feeling rejuvenated, Lovato sings: "Now I'm out here looking like revenge/ Feeling like a 10, the best I ever been," and, "Feeling inspired 'cause the tables have turned/ Yeah, I'm on fire and I know that it burns."

Lovato also sings: "Now payback is a bad b***h, and baby I'm the baddest/ You f*****g with a savage, can't have this."

Within hours, the track became a trending topic on Twitter with fans praising Lovato's confident new sound. One fan commented: "Demi invented soul-trap infused R&B-pop! #SorryNotSorry
If you call this generic and bland, you're literally clawing for ways to hate."

Another enthused: "Demi Lovato took all the hate she got and created this masterpiece, we stan a genius everybody. We shall stan forever."

One other supporter predicted: "This song is the new summer hit," while another chimed in: "A new era has started for my girl @ddlovato and I love it."

Listen to Demi Lovato's Sorry Not Sorry:

It did not take long for the single to top the iTunes charts in several countries including Brazil and the upcoming music video will no doubt generate even more interest with Jamie Foxx and Paris Hilton previously confirming their cameos.

The debut came just hours after the Heart Attack singer penned a heartfelt letter thanking fans for their support in recent months, which included her split from longtime boyfriend Wilmer Valderrama. Lovato wrote in the Instagram post: "I just got back from the most inspiring trip to Hamburg. The trip reminded me, once again, that no matter where we live or what our cultural backgrounds are, having emotional human connection and love are absolutely crucial for our existence and survival.

"Over the recent months, I've made a conscious decision to slow down a bit, to hug and meet more of you, and to take more time learning about some of your personal journeys too. Thank you for allowing me to take the time I needed at the end of last year to step away from all the craziness."

Lovato released her last album, Confident, in 2015 and reached number two on the US Billboard 200 chart. The album hosted the singles Cool For The Summer, Confident and Body Say.