Sharon Osbourne has called Lady Gaga a hypocrite over her public criticism of bullying.

In a new extract from her upcoming autobiography Unbreakable, the X Factor judge says that the 'Applause' star's inability to stop her fans from sending death threats to Kelly Osbourne was inexcusable. She said:

"By not repudiating her fans' bullying, she was condoning it. That's why I called her a hypocrite. I was so disappointed because I had always been a huge fan. I have been to three of her shows and she's undeniably a very talented woman. But you can't bang on about being anti-bullying and then refuse to tell your fans to stop haranguing other young women with nasty threats."

Sharon Osbourne also called into question Gaga's decision to bring a therapy bus for fans on tour with her, calling it a "publicity" ploy. She said:

"On Gaga's last tour there would be a bus at each venue and she put therapists in there for kids who were bullied. I felt it was just a publicity stunt. Perhaps the next time she has one of these mobile counselling stations she should go in and ask the therapist for advice on setting good examples for her fans."

A rift between the Osbournes and Gaga started earlier this year when the latter penned a letter to Kelly to criticise her for panning people on TV show the Fashion Police.

Gaga fans soon sent death threats to Osbourne on Twitter, with the Brit also suggesting that the 'Born This Way' star was a hypocrite for not publicly encouraging her devotees to stop the abuse.

Sharon Osbourne's book meanwhile will be released on October 10.