Marie Osmond has been branded an ‘ungrateful celebrity’ by her former manager.

Karl Engemann has sued Marie, claiming he singlehandedly helped rebuild her career, but that she fired him 18 months into a five-year contract and then defamed him.

Engemann’s lawyer, Larry Stein, calls the attacks against his client ‘scandalous and ‘scurrilous’.

Stein claims that Marie is now making a bundle - $125,000 a show in Las Vegas with her brother Donny - and Stein says it’s all Engemann’s doing.

Stein said: “Shamefully, Ms Osmond has fired Mr Engemann 18 months into a five-year written contract and seeks to enjoy the fruits of his labours without compensating him for his work.”

However, Marie’s lawyer Marty Singer claimed that Marie fired Engemann - the father of Larry King’s wife, Shawn - “because he acted in an inappropriate, improper manner and breached his fiduciary duty to Marie”.

Singer added: “Engemann defamed Marie and she’ll go after him for substantial monies and will establish he has no right to more commissions.”

The matter is currently before a private arbitrator.