The troubled singer is set to defy the wishes of her family - including dad Jamie, who is co-conservator of her estate, and ex-husband Kevin Federline - to appear in the proposed fly-on-the-wall MTV documentary.

The proposed programme will focus on Britney's attempts to get her life and career back on track following her breakdown earlier this year.

A source told Britain's Daily Star newspaper: "Britney's dad is furious. He thinks it's a big mistake and doesn't want anything to do with it. But Britney thinks it will help her custody battle for her sons."

Britney's mother Lynne is said to be desperately trying to talk her daughter out of the show because she fears the 'Toxic' singer will use it as a platform to speak out before Lynne's tell-all book is published.

A worried friend of Britney - who has two sons Sean Preston, two, and Jayden James, 23 months, with Kevin - said: "This could be the biggest car crash television moment of all time."

Britney has previously starred in an MTV reality show with Kevin, 'Britney and Kevin Chaotic' which aired in 2005. It was cancelled after one season and mainly featured home videos the couple had made.

Photo: WireImage.com