Former Zero 7 singer, Sia, has unveiled a new album track during a concert in San Diego on Thursday (September 8).

Sia followed up the performance with a tweet of the youtube clip (below) and added: "new song live, 'HOSTAGE' taster of new album produced by nick valensi, out next year sometime."

Sia currently features on the David Guetta's single 'Titanium'. The as-yet-untitled album will be her sixth studio album.

Earlier this year, the singer threatened to quit the music business after Perez Hilton outed her as bisexual, and her new found fame caused her to get withdrawn and depressed.

Speaking to The Times at the time, the Australian singer said: "When I was outed by Perez Hilton as bisexual, I suddenly started being asked a lot of personal questions, which was really difficult. I'd had a relationship with a woman when I was 20, but nobody cared then. 

"As it came at the same time as my fame, it made me withdraw, and I started to have panic attacks. It was then that I was prescribed antidepressants - fame made me develop a panic disorder." 

Watch the video clip that Sia tweeted of 'Hostage' below: