Beyonce Knowles has denied leaking online a brand new track Justin Timberlake reportedly wrote for her. 

Timberlake's representatives are baffled how the recording of him performing new track 'Magic' found its way onto the Internet.

It has been alleged the song was written for Beyonce - but her manager father Mathew Knowles denies knowing anything about the controversy.

He tells Us Weekly magazine, "(The track) was never presented to me personally. We have a good relationship with Justin."