A top journalist is about to reveal all about Britney Spears' reported suicidal tendencies in a new book about the troubled star.

Ian Halperin spent 18 months as an undercover paparazzo trying to get close to Spears and has now written about his encounters with the pop singer.

He tells Life and Style magazine she twice tried to kill herself: "The suicide attempts are true. I know all the details about both of them."

And a family insider is supporting Halperin's claims, stating Spears threatened suicide many times during the time Halperin was investigating her -- from November 2006 until last month.

Halperin also claims he saw Spears using drugs: "I partied with her and was able to really monitor what type of stuff she was using. It's very concerning."