A drawing by late South African leader Nelson Mandela of the door of his prison cell on Robben Island -- where he was held for 18 years -- will be put up for auction in early May in New York.
Bonhams, which will host the sale on May 2, has put the value of "The Cell Door, Robben Island" -- completed in 2002 by the Nobel peace laureate -- at $60,000 to $90,000.
The work will be part of a sale of modern and contemporary African art.
'Poignant' and 'personal'
"The word 'iconic' is so overused but to have a drawing of one of the most important men of the 20th century... would be a remarkable thing," Giles Peppiatt, the auction house's director of modern African art, told AFP.
"It's the first time this work has ever been exhibited in public. It's also the first work by Nelson Mandela ever to be sold in the open market."
The wax pastel crayon drawing shows a few bars of the cell door and a key in the lock, sketched in purple.
The work is one of the few that Mandela -- who was jailed for 27 years in total and inspired the struggle against apartheid -- kept until his death in 2013.
"It was a very personal, very poignant work for him," Peppiatt said, explaining that Mandela embraced art as a hobby after leaving South Africa's presidency in 1999.
"He had more time on his hands," he said.
Until now, Mandela's daughter Pumla Makaziwe Mandela had the work in her possession.
South Africa's first black president did a total of 20 to 25 drawings, according to Peppiatt. Some were reproduced as lithographs to raise money for the Nelson Mandela Foundation.
Mandela was jailed from 1962 to 1990. He was held at Robben Island off Cape Town from 1964 to 1982. Mandela served as South African president from 1994 to 1999.