Denis Goldberg – an anti-apartheid activist who has been former Mandela's friend for more than half a century – told Agence France-Presse on Friday that the issue of turning off life support was discussed and ultimately dismissed.
"I was told the matter had been raised and the doctors said they would only consider such a situation if there was a genuine state of organ failure," Goldberg said.
"Since that hasn't occurred they were quite prepared to go on stabilising him until he recovers."
The 80-year-old Goldberg was convicted along with Mandela in 1964 for their fight against white-minority rule.
He visited the former president in hospital on Monday.
A court document filed by a lawyer for Mandela's family nine days ago stated the 94-year-old was "assisted in breathing by a life support machine".
"The Mandela family have been advised by the medical practitioners that his life support machine should be switched off," the court filing read.
"Rather than prolonging his suffering, the Mandela family is exploring this option as a very real probability."
The document – which was designed to press a court to urgently settle a family row over the remains of Mandela's children – also stated that Mandela was "in a permanent vegetative state".
South Africa's presidency has stated that is not now the case, but has refused to give further details of his condition, citing the need to respect Mandela's privacy.
Mandela was rushed to hospital on June 8 with a recurring respiratory infection.
Meanwhile, amid the highly publicised Mandela family fall-out, Nelson Mandela's grandchildren paid him a routine visit on Friday morning. Zaziwe Dlamini-Manaway, Swati Dlamini and Ndaba Mandela drove into Heart Mediclinic Hospital in a red Range Rover to see the ailing statesman, whom the office of the presidency insists is in "a stable but critical condition".
The festive atmosphere outside the hospital has since died down following two weeks of crowd management by the South African police. Small groups from various institutions, including Ikwekwezi FM staff and listeners held a prayer.
Parliament also held its own prayer session in Cape Town on Friday. – Additional reporting by Khutala Adams