Angelina Jolie's Oscar nomination celebrations have been marred by reports her former bodyguard is planning a tell-all which will set out to prove the actress moved in on partner Brad Pitt when he was still married to Jennifer Aniston.

Sources claim the actress, who was nominated for a Best Actress Academy Award on Thursday, is seeking legal counsel to block Mickey Brett's expose, which will also expose intimate details of her courtship and sex life with Pitt.

An publishing insider tells In Touch Weekly magazine, "He (Brett) knows everything about Angelina. It's going to be one of the most explosive books ever written."

Brett, who headed up the Jolie/Pitt's security detail when the couple went into hiding in Namibia before the birth of baby daughter Shiloh in 2006, was reportedly fired by Pitt last year.