The Timber singer has been locked in a bitter court dispute with the two parties since last year (14), when she accused Dr. Luke of a string of offences, including sexual harassment, sexual assault and emotional abuse.

In the ensuing paperwork, Kesha added Sony Music chiefs to her lawsuit, claiming they knew about Dr. Luke's alleged behaviour and declaring that because she is tied to the record label, she "can't work with music producers, publishers, or record labels to release new music".

Kesha, who is seeking to be released from her contract with the defendants, asked Sony officials for permission to record new material in an effort to press on with her career, insisting the unexpected hiatus could seriously jeopardise her career, but label representatives refused.

Now they have lodged a new response to the accusations, dismissing Kesha's worries about her extended break and using Adele, Justin Timberlake and D'Angelo as examples of artists who have made huge comebacks after taking time out of the public eye.

Lawyers for Sony claim they have invested too much in Kesha to just let her go, revealing they have spent more than $11 million (£7.3 million) on her career to date, which has so far banked her $3 million (£2 million) in royalties alone, according to documents obtained by

They also maintain Kesha has been keeping a high profile by booking guest appearances in TV show Jane the Virgin and the movie Jem and the Holograms, which actually became a major flop upon its North American release in October (15).

Sony bosses and Dr. Luke have denied all of Kesha's sex accusations, while the producer has filed a countersuit against the pop star for defamation and extortion.