The 'Real Housewives of Beverly Hills' star believes the 'Can't Fight the Moonlight' singer - who was treated for anxiety last year in a rehab clinic - ''may be unstable'' and thinks she needs to undergo further treatment.
The 40-year-old reality TV star, who is promoting her memoir 'Drinking & Tweeting and other Brandi Blunders,' told Life & Style magazine: ''LeAnn needs to get help. She may be unstable, and I am concerned. I want to protect (my children). I want to make sure she's as healthy as she can be.
''There are clearly some issues going on, and I need to know my kids are okay when they're with (LeAnn)!''
A spokesperson for 30-year-old LeAnn - who is happily married to Brandi's ex-husband Eddie Cibrian - dismissed the reality star's latest attack and defended the singer, saying: ''This is a ploy to sell more books. If anyone needs help, it's Brandi. That should be obvious to anyone who's read her tweets.''
Brandi - who shares two sons, Mason, nine, and Jake, five, with Eddie - previously said she wanted to end her long running feud with LeAnn.
She said: ''I'm ready to put it behind me ... This [book] is my final chapter, this is me closing the door on our public fight. I want it out of the media, I'll just deal with it as best [as] I can with them.
''We don't have the best communication or relationship right now but, I'm hoping we can change that. I don't think we'll be friends, but I hope we can co-exist peacefully.
''I think once she has a child of her own, I think she will understand boundaries and what's respectful to do and how to handle things a little better.''