Plans to auction off the key that kept Nelson Mandela, the former president of South Africa and legendary anti-apartheid activist, behind bars are off.

The auction house, New York City-based Guernsey's, planned to hold an auction of items belonging to Mandela — including the key to his Robben Island prison cell — later this month. Bidding was expected to begin at $250,000.

Mandela was held at Robben Island prison for 18 of his 27 years behind bars in South Africa. In 1964, he was sentenced to life in prison for plotting to overthrow South Africa's racist apartheid system. In 1994, he was elected the nation's first Black president and remains a global icon.

Mandela died in 2013 at the age of 95.

Officials in South Africa rejected Guernsey's plans, arguing the key is a part of South African history and belongs to the country.

In a statement that commends Guernsey's for canceling the auction of the key, South Africa's Minister of Sport, Arts and Culture Nathi Mthethwa said: "The key symbolizes South Africa's painful history whilst also representing triumph of the human spirit over evil."

"This key is living proof of South Africans' long walk to freedom and belongs to the people of South Africa," he continued. "It therefore must rightfully be returned to the country."

The auction house has begun efforts to return the key to South Africa, Mthethwa added.

Guernsey's president Arlan Ettinger shared details of the items originally set for auction, in an interview on CNN's Michael Smerconish's SiriusXM podcast.

Ettinger said the Robben Island key, an exercise bike Mandela used in his cell, as well as a tennis racquet he had in prison, were previously owned by Christo Brand, a prison guard who later became close friends with the anti-apartheid leader.

Ettinger also shared details of the other items previously up for auction that were given to Guernsey's by the Mandela family. Those included: the shirt worn by Mandela when he was released from prison, a blanket gifted to Mandela by former U.S. President Barack Obama and First Lady Michelle Obama, and a charcoal drawing of a broken chain signed by Mandela.

Guernsey's says on its website that its Nelson Mandela auction is postponed for now as the South African Heritage Resources Agency review the other pieces set for auction.

It's unclear whether the auction house plans to continue the sale of the rest of the items offered by Mandela's family.

Details of the when or how the Robben Island key will return to South Africa will be released to the public at a later time.

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