David Guetta released Sia's version of 'Titanium' without telling her

Sia has revealed her embarrassment after David Guetta released the version of 'Titanium' that contained her vocals, which was only ever intended as a demo.

Sia, who has released five studio albums and written for huge artists including Katy Perry, Rihanna and Britney Spears, has nonetheless always shunned mainstream fame.

When she wrote 'Titanium' for David Guetta, and recorded a demo, it was intended for Mary J. Blige, who even recorded vocals for the song. However, Guetta eventually decided to release Sia's demo version instead.

Speaking to The Sunday Times, the singer revealed her horror over Guetta's decision: "I was like, 'What the fuck?' I'd spent such a long time building what I thought was my own credible music career, and I found myself embarrassed by the commercialism of that music." She then added: "But, of course, when it buys you a house, it stops feeling like such a bad thing."

The singer also acknowledged that the song turned out to be "the best thing to happen to my career."

Sia's new album, 1000 Forms Of Fear, is due for release on 8 July.