Cher has revealed her frustration after a demo of a new Lady Gaga duet leaked online.

A rough version of the song 'The Greatest Thing' - which has been mooted since 2011 - recently found its way online.

This provoked Cher into posting her digust on Twitter, with the veteran singer proclaiming:

"Just heard TGT ! F*CK ! IT’S NOT EVEN THE RIGHT F*CKING VERSION!!! WHY DO PPL THINK THIS KINDA LEAKING SH*T IS OK ! I’m so Fg DISSAPOINTED."

She added: "Disappointed( Ive Sat on fkng song 4 over a yr )NOW SOME ASSHOLE LEAKS WRONG VERSION ! GaGa’s SINGLE IS GREAT, & THAT’S ALL THAT MATTERS."

Her praise of Gaga's new single 'Applause' meanwhile was taken well by the 'ARTPOP' lady, who tweeted:

"I love you @cher! Thank you for the support, you're the greatest thing!"