Kelly Clarkson has recorded a mystery duet.

The 'I Do Not Hook Up' singer - who recently performed on Simon Cowell's last ever 'American Idol' - has headed back into the studio to work on her the follow-up to 2009's LP `All I Ever Wanted' and has told fans she has already laid down one collaborations.

She tweeted: "Officially recorded the first song for my 5th album today! It's so awesome and is a duet but I can't tell you who quite yet :). (sic)"

Earlier this year it was rumoured that singles from the upcoming LP had been leaked over the internet. However, Kelly - who shot to fame after winning the first series of `American Idol' in 2002 - insisted the leaked tracks were not hers.

She blasted on twitter: "Cleopatra is NOT a song on my next record! It was written for another artist! I have no idea how it leaked, it's a rough demo, unfinished! I'm so tired of disrespecting, lying, sneaky little trolls that pretend to be human."