South Africans are mourning the death of Anglican Bishop David Russell who Archbishop Emeritus Desmond Tutu has described as an "outstanding" stalwart" in the fight against apartheid.

Russell, the retired Anglican bishop of Grahamstown in South Africa's Eastern Cape province died in Cape Town of cancer on Sunday, aged 75, the South African Press Association (SAPA) reported.

Tutu said Russell had spoken fluent Xhosa and "When he became bishop of Grahamstown he proved to be a splendid trainer of bishops. All his suffragan bishops later became heads of dioceses, including the current archbishop of Cape Town," Tutu said.

"We thank God for this outstanding servant. May he rest in peace and rise in glory."

Archbishop Thabo Makgoba of Cape Town said: "With David Russell's death, an era passes for the church and its prophetic and courageous ministry, especially to the poorest of the poor.

"From the earliest days of his ministry as a priest, he was radical in his identification with the poor and oppressed. [Black Consciousness activist] Steve Biko with whom he worked closely, called him 'a friend, an equal... a comrade'."

Russell studied at the University of Cape Town and Oxford University.

Makgoba said Russell played an important role in the Eastern Cape in the 1970s in drawing attention to the plight of people forcibly removed from their homes under apartheid and dumped to starve in areas such as Dimbaza.

"Later, as a chaplain to migrant workers in Cape Town, he campaigned against the cruel removals, in the middle of winter, of families who defied the pass laws and came to Crossroads to live with their husbands and fathers," the archbishop said.

"When the apartheid government sent in bulldozers to destroy their shacks, he was willing to put his life on the line."

He also walked from the Eastern Cape to Cape Town to make a statement on the migratory labour system, Tutu said.

Makgoba said an admirer of Russell had posted on social media platform Facebook last week, recalling the image of Russell lying "spread-eagled" in front of a bulldozer in Crossroads.

"When the government imposed a banning order on him, he defied it, breaking it in multiple ways to attend a meeting of the church's provincial synod and to motivate a resolution expressing the church's understanding of those who had resorted to armed struggle."

Russell repeatedly challenged the church on theological grounds to reverse its opposition to blessing same-sex unions.

"He also challenged the democratically elected provincial government of the Eastern Cape for its failures in areas such as health and education," Makgoba said.

"As one who served as Bishop David's suffragan bishop in Grahamstown and was mentored by him, I feel his loss keenly. Not only the church but the nation, which honoured him for his service with the Order of the Baobab in Silver, mourns this son of the soil."

Makgoba said on behalf of his family, the diocese of Cape Town, the synod of bishops and the broader church, they sent their condolences and prayers to his wife Dorothea and to his sons Sipho and Thabo.

"May this pastor, prophet, theologian and fierce fighter against injustice rest in peace until we meet again."