ANC veteran and former Rivonia trialist Andrew Mlangeni was still in hospital on Friday, his son Sello Mlangeni said.
"He is getting better," said Mlangeni, after sharing earlier this week that his father had been unwell in the past two weeks and had been in and out of hospital.
The 93-year-old was admitted to an undisclosed hospital in Cape Town on Wednesday to be treated for an infection.
In a tweet, the Ahmed Kathrada Foundation said that on October 15, Mlangeni would mark 29 years since his release from prison with several other Rivonia trialists.
Mlangeni is known to still attend social justice events, in spite of his age. It is only he and Denis Goldberg left from the group of people - that included former president Nelson Mandela - banished to Robben Island by the apartheid justice system in 1964.
Anglican Archbishop Emeritus Desmond Tutu was admitted to hospital in Cape Town last week, but the Tutu Foundation customarily does not divulge details of his stay, in spite of a request for an update.
Former foreign affairs minister Pik Botha, who was also admitted to hospital last week, was discharged and back home, his wife Ina said on Thursday.