An old prison letter of late rapper Tupac says he broke off his love affair with Madonna because she was white.

The American rapper poured out his heart to the singer in an extremely revealing letter he wrote in jail, TMZ reported.

Tupac stated in the letter: "For you to be seen with a black man wouldn't in any way jeopardise your career, if anything it would make you seem that much more open and exciting."

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The "All Eyez on Me" hitmaker then confesses, "But for me at least in my previous perception I felt due to my 'image' I would be letting down half of the people who made me what I thought I was."

Tupac clearly knows he devastated Madonna by the rejection, saying, "I never meant to hurt you."

According to TMZ, the letter will go up for auction July 19-28 at Gotta Have Rock and Roll.

Starting bid is $100k and it's expected to fetch a lot more. The last letter written by Tupac sold for more than $170k.