The image of Nelson Mandela with his fist raised on the day of his release from 27 years in jail has been immortalised in a bronze statue unveiled today outside a prison where he was held.

Mandela, who celebrated his 90th birthday in July, braved a cold, rainy day to see the statue, which weighs about 490 kilogrammes and stands slightly more than three metres tall at the entrance to Groot Drakenstein prison near Cape Town.

"During the 27 years of imprisonment he probably became the most famous political prisoner in the world. I cannot think of a figure who has so many accolades and awards," South African Minister of Arts and Culture Minister Pallo Jordan told a large gathering of media, government ministers and diplomats.

Tokyo Sexwale, one of South Africa's richest businessmen and whose Family Foundation commissioned the statue, said the statue was highly symbolic.

Sexwale, a former Robben Island prisoner alongside Mandela, was at the unveiling, along with Mandela's wife Graca Machel and former wife Winnie Madikizela-Mandela, who walked alongside Mandela on his release from prison.

Mandela, wearing a black coat over one of his trademark colourful shirts, waved during the ceremony and held hands with schoolchildren, who sang happy birthday to him.

He spent his final months in prison at Groot Drakenstein before being freed in 1990. He became South Africa's first democratically elected president in 1994.

Britain honoured Mandela with a bronze statue at London's Parliament Square last year. Another bronze statue of Mandela is located at one of Johannesburg's main shopping malls.

The statue's white and black marble signify the racial reconciliation Mandela epitomised, while the shoes are typical of prison gear, and the striding left leg captured Mandela's formative leftist ideology, Sexwale said.

"It was a great privilege to do it and I hope I did justice to such a great man," sculptor Jean Doyle told Reuters.