"We confirm our earlier statement released this afternoon after President Jacob Zuma visited Madiba in hospital that Madiba remains in a critical, but stable condition," said the Thursday release from Zuma's office, using the clan name for Mandela.
"The doctors deny that the former president is in a vegetative state," the statement continued.
A former anti-apartheid leader and South Africa's first president after apartheid ended, Mandela, 94, has been in hospital since June 8 with a recurring lung infection.
Agence France-Presse reported Thursday that court documents filed on June 26 indicate that Mandela is on life-support.
"He is in a permanent vegetative state and is assisted in breathing by a life-support machine," lawyers for some of Mandela's family said, according to AFP. "The Mandela family have been advised by the medical practitioners that his life support machine should be switched off.
The court documents were filed by members of Mandela's family as part of their bid to secure the return of the bodies of three of his children to the family burial plot in his hometown of Qunu. The bodies had been taken by Mandela's grandson, Mandla Mandela, the oldest male heir and a tribal chief, who moved them to his village of Mvezo.
Following a court order, the bodies were returned to Qunu on Thursday and reburied in a ceremony that included the singing of hymns.
Also Thursday, Nelson Mandela's wife, Graca Machel, said her husband is sometimes uncomfortable but seldom in pain.
"Whatever is the outcome of his stay in hospital, that will remain the second time where he offered his nation an opportunity to be united under the banner of our flag, under the banner of our constitution," Machel said at a fundraising drive for a children's hospital to be named for Mandela.