The rapper wrote the note while he was in jail serving a sentence stemming from a sexual assault conviction a year before his death in 1996.

It was addressed to his friend Nina Bhadreshwar, who worked for the Death Row Records label.

In the rambling letter, Shakur wrote, "(Many) never survive the next level of Thug Life... They become addicted to death. A True Boss Playa knows when to advance (sic)... U must play the game, not let the game play u (sic)... A regular Playa plays women (sic)... a Boss Playa plays life (sic). A Boss Playa is a thinker, a leader, a builder, a moneymaker, a souljah, a teacher and most of all, a man (sic)! I want all my homiez to know there is another level (sic)."

The artefact is set to be sold off as part of an auction by Moments in Time.

It is expected to fetch around $225,000 (£140,625), according to the New York Post.

Bhadreshwar says of the letter, "He (Shakur) enclosed a five-page essay on his view of the rite of passage of a young black male in America. And that was the beginning of our real correspondence."

The rapper died in a shooting less than a year after he was released from prison.