Two new Katy Perry tracks have leaked online.

The songs 'Unconditionally' and 'Birthday' from the singer's forthcoming album, 'Prism', have surfaced on the internet ahead of the record's scheduled release on Tuesday (22.10.13).

'Birthday' is an R&B dance track which has been likened to Whitney Houston's early singles.

'Unconditionally' - produced by frequent collaborator Dr. Luke - is a four-minute love song, and features the lyrics: ''I'll walk through this storm, I would / All because I love you.''

The leak is bound to be a disappointment for Katy, who has gone to great lengths to keep her new material under wraps ahead of the album's release.

It is rumoured Katy will perform 'Unconditionally' - set to be her next single - live for the first time when she appears at the MTV European Music Awards (EMAs) on November 10.

Earlier this week Katy also released 90 second preview clips of all the tracks on 'Prism', much to the delight of fans.

One twitter user, KatySlaysUrFav, wrote: ''Prism sounds and looks so good i can't wait to eat the physical copy just to have it inside me.''