A prominent South African anti-apartheid activist, Ben Turok, has died at the age of 92.

He was a lifelong member of the African National Congress (ANC), but became a fierce critic of the corruption within its ranks after it took power in 1994.

"He was always outspoken and dedicated his whole life to fighting for freedom, equality and social justice in South Africa," his son Ivan Turok said in the statement.

"He was a loyal, lifetime member of the ANC, but retained an independent perspective throughout. His wisdom and counsel will be sorely missed," he added.

Local media reported that Turok - an economics professor who was also a former member of the South African Communist Party (SACP) - had been in hospital in Cape Town for some time.

He had spent three years in prison for his anti-apartheid activities,and later went into exile before returning to South Africa after the unbanning of the ANC, SACP and other political movements in 1990.

South Africa's President Cyril Ramaphosa led tributes to Turok on Twitter, pointing out that he was the "only surviving member of the original underground leadership" of the SACP.

See tweets below: