Justin Bieber Threatens To Sue ... Take Down The Naked Pics Or Else!!

Justin Bieber and his team are sending a strong message -- the nude photos of him published this week invaded his privacy, and anyone who posted them should take them down immediately.

TMZ has confirmed Bieber's legal team has sent multiple cease and desist letters to news outlets that published the pics, saying remove 'em or else. They claim the photos were taken without Bieber's knowledge. They show a naked Bieber in Bora Bora ... right before jumping into a pool.