Britney Spears' Ex-Nanny -- Jamie Spears NEVER Attacked Sam Lutfi

Jamie Spears never laid a finger on Sam Lutfi's solar plex, despite Lutfi's testimony that Britney's daddy punched him in the chest and threatened to kill him -- so says Britney's ex-nanny Leah Frand.

Frand tells us Lutfi's claims are utter BS.

Frand says she should know, because she worked for Britney for 6 months in 2007 -- at the height of Brit's crazy period, around the time she was 5150'd and sent to UCLA Medical Center.