Video footage of a young Zindzi Mandela reading out her father, Nelson Mandela's, rejection letter to then president PW Botha has gone viral since confirmation of her death on Monday.

Zindzi was speaking at a mass gathering in Soweto, Johannesburg in 1985.

The letter was Nelson Mandela's response to Botha's offer of freedom on condition that he “unconditionally rejected violence as a political weapon”.

“I am surprised at the conditions that the government wants to impose on me. I am not a violent man. My colleagues and I wrote in 1952 to Malan asking for a round table conference to find a solution to the problems of our country, but that was ignored. I am in prison as a representative of the people and of your organisation, the African National Congress, which was banned. What freedom am I being offered whilst the organisation of the people is banned?” reads part of the letter.

The former statesman said he was not prepared to sell his birthright, nor those of the people to be free.

"I cherish my own freedom dearly, but I care even more for your freedom. Too many have died since I went to prison. Too many have suffered for the love of freedom. I owe it to their widows, to their orphans, to their mothers and to their fathers who have grieved and wept for them. Not only I have suffered during these long, lonely, wasted years. I am not less life-loving than you are. But I cannot sell my birthright, nor am I prepared to sell the birthright of the people to be free. I am in prison as the representative of the people and of your organisation, the African National Congress, which was banned."

You can read the full letter here.

The daughter of Nelson Mandela and Winnie Madikizela-Mandela died at a Johannesburg hospital on Monday morning.

Her death has been described as “sudden”.

On social media, she has been hailed for her bravery and for tackling “real issues.”