Various organisations paid tribute on Friday to struggle veteran Curtis Nkondo, South Africa's former high commissioner to Namibia, who died on Thursday.
The ANC said Nkondo, 82, had died after being taken to a hospital in Johannesburg two weeks ago after a long illness.
"His death leaves a large gap in the ANC ranks," the party said. "The democratic South Africa owes it to his memory and his lifelong struggle to intensify our activities in every area of life, to end poverty and unemployment.
"He was always clear to his political allegiance and took pride in putting people first."
Nkondo was born on February 1, 1928, in Louis Trichardt. He was married with three sons and two legally adopted grandchildren.
He completed his high school diploma in 1952 and became a high school teacher. He was subsequently appointed as the headmaster at Lamula High School in Meadowlands.
He was elected the chairman of the Soweto Teachers Action Committee and later suspended from teaching by the apartheid education department.
In 1983 he was elected as the vice-president of the United Democratic Front in Cape Town. In 1985, he was elected chairman of the Release Mandela Campaign and became president of the National Education Union of South Africa (Neusa).
After the first democratic elections in 1994, he became a member of the Gauteng Provincial Legislature and served on various bodies, such as the Association Against Woman and Child Abuse, the Etwatwa Community Trust, the Soweto Education Co-ordinating Committee and the ANC Gauteng Disciplinary Committee.
The South African Democratic Teachers Union said Nkondo had dedicated his life to fighting for a better quality of education for all.
"Comrade Nkondo believed that better quality education for all went hand in hand with political freedom," said Sadtu general secretary Mugwena Maluleke.
Nkondo became the first deputy president of Sadtu at its launch in 1990.
International Relations and Co-operation Minister Maite Nkoana-Mashabane said: "On behalf of government and the diplomatic community, I wish to express our heartfelt condolences to the family of Nkondo during these trying moments. Our thoughts and prayers go out to the them."
The SA Communist Party said Nkondo was a "life-long revolutionary and champion of democracy, justice and equality in our country".
"He remained an energetic commentator on South African political life and a committed Marxist-Leninist until his death... He lived his life as a committed and disciplined democratic activist and serves as a role model to all who are committed to liberty and justice," said the SACP.
Nkondo is survived by his wife, Rose, and his three sons, Reavell (Ricky), Ruskin and Ephraim. - Sapa