None of the nude photos actually show Rihanna's face, but were leaked in combination with non-nude photos of a woman that resembles Rihanna.
"She is freaking out," a source told News Of The World.
"She was on the road to recovery after a terrible few months.
"She has no idea how these pictures have been leaked but she's determined to find out."
Rihanna's record label, Def Jam, has not confirmed whether the photos are of their young star but has reportedly demanded the "unauthorised photos" be taken down, because they "violate the artist's rights".
Rihanna has insisted in the past she would never pose nude for Playboy, saying "my mother would kill me if I posed nude."
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