Sisulu was the son of late anti-apartheid struggle veterans Walter and Albertina Sisulu, and was a liberation activist in his own right.

Details about his death are still sketchy but a source close to the Sisulu family said the family would release more information about the incident during the course of the day.

He reportedly collapsed at his home in Greenside, Johannesburg, this morning.

Sisulu’s siblings include the Speaker of Parliament Max Sisulu and Public Service and Administration Minister Lindiwe Sisulu.

At the time of his death, he was listed as the chairperson of the boards of Dirleton Minerals and Energy and Savanah Resources.

He was the CEO of the SA Broadcasting Corporation between 1994 and 1997, and was credited with transforming the broadcaster from a state broadcaster.

Prior to that, he edited the anti-apartheid newspaper New Nation, which was a vocal critic of the government.

A decorated journalist, he became a Nieman journalism fellow at Harvard in 1984 and also won the 1987 Louis M. Lyons Award for Conscience and Integrity in Journalism.

Sisulu, whose journalism career started at the Rand Daily Mail in 1975, was described by the Nieman Foundation as a man who used “ideas and the printed word” as a weapon against an opponent who answers with force.

He was detained without trial for two years for his political activism from December 1986 under the state of emergency.

Veteran journalist and former City Press editor-in-chief Mathatha Tsedu wrote on his Facebook page: “The sad news that Zwelakhe Sisulu has passed away brings memories of struggles of black journalists and media workers which he also led so ably as president of the Writers Association of SA and later the Media Workers Association of SA. For that he was banned and detained and tortured, but never wavered.”

President Jacob Zuma described Sisulu as a “distinguished South African and patriot,” and said he had learnt with shock and sadness about his death.