She'd better brace herself for more legal bills and security costs.

Britney Spears has reportedly received death threats while on her current Circus tour, attracting the unwanted attention of a dangerous stalker.

"Britney has received anonymous death threats over the phone and in the mail, and her worst fear is a kidnap plot against (sons) Sean or Jayden."

"She's been having terrible nightmares since then and she wakes up in the middle of the night crying for her boys," sources close to the star say.

Who would want to hurt such a fine performer?

That sounds terrible, but no doubt Jamie Spears is doing what he can to keep his daughter safe, secure and prospering by any means necessary.

All she can do is keep performing. Click to enlarge some hot Britney Spears pictures from her 90-minute set in Washington, D.C., last night ...

[Photo Credits: Splash News Online]