Britney sings autographs for fans at an earlier X Factor USA audition.

X Factor USA judge Britney Spears furious with many of the claims made by former associate Sam Lutfi in a California court.

He is testifying about a very dark part of Britney's life and some of the claims have upset Spears, a report has claimed.

The 'X Factor USA' judge's former manager is suing her parents for defamation and during the trial he has claimed Britney was addicted to drugs when he managed her but the singer, who has gotten her life back together following a heavily publicized breakdown in 2008, is upset by his revelations.

A source said: ''Over the past four years you'd hear Britney's name and the first thing you'd think of was shaved head, psych hold, umbrella.

''But she got her life straightened out and now you think music, glamor, that big smile. The court case couldn't have come at a worse time.''

Britney's friends are also worried about the star having to relive her past troubles.

The insider added to In Touch Weekly magazine: ''She's long battled mental health issues so to be reminded of this time in her life, when she almost died, is devastating. No one should have to relive what she went through.''

© Bang Showbiz