Court documents obtained by AFP news agency show that doctors have advised that Nelson Mandela's life support be turned off.
The files, dated June 26, describe the 94-year-old as being in a "vegetative state".
South Africa's President Jacob Zuma has visited Mandela in hospital in Pretoria this afternoon and he said the anti-apartheid leader remains "critical but stable".
A Mandela family court affidavit, obtained by the Mail and Guardian newspaper, said Mandela is on life support in the form of a breathing respirator.
Meanwhile, Mr Mandela’s wife said the former president is sometimes uncomfortable but seldom in pain while being treated in a hospital.
Graca Machel spoke about her husband’s condition at a fundraising drive for a children’s hospital that will be named after the 94-year-old anti-apartheid leader.
“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,” she said.
Mr Mandela was imprisoned for 27 years during white racist rule and was freed in 1990 before being elected president in all-race elections. He won the Nobel Peace Prize with former President F.W. de Klerk.