A June 26 court filing obtained by AFP described Mandela's "perilous" health and appears to show for the first time just how close the critically ill 94-year-old came to death.

"He is in a permanent vegetative state and is assisted in breathing by a life support machine," lawyers said on behalf of 15 Mandela family members including his wife and three daughters.

"The Mandela family have been advised by the medical practitioners that his life support machine should be switched off.

"Rather than prolonging his suffering, the Mandela family is exploring this option as a very real probability."

The filing pressed a South African court to urgently resolve a bitter family feud over where the remains of three of Mandela's children should be buried, which could have implications for Mandela's own final resting place.

On the day the document was drafted, President Jacob Zuma abruptly cancelled a trip to Mozambique to confer with Mandela's doctors amid fears the 94-year-old may be close to the end.

Zuma, Mandela family members and his close friends have since reported his condition has improved.

South African presidential spokesman Mac Maharaj told AFP on Friday that Zuma's office "had not been party" to the court material and would not speculate on its content.

"We did not file any document and we are not saying that it's true or not true," he said.

Maharaj told AFP that doctors had since said Mandela is not currently "in a vegetative state", but the spokesman refused to comment on Mandela's previous condition.

"We do not go into clinical details of his condition for reasons of doctor-patient confidentiality," said Maharaj, also citing the "dignity of the former president".

Denis Goldberg, one of the men who was convicted with Mandela in 1964 for their fight against white-minority rule, told AFP Mandela was clearly conscious when he visited him on Monday.

"He is clearly a very ill man, but he was conscious and he tried to move his mouth and eyes when I talked to him," Goldberg said.

"He is definitely not unconscious," he added, saying "he was aware of who I was".

Mandela, who spent 27 years in prison for fighting white-minority rule and went on to lead the process of racial reconciliation as South Africa's first black president, has now spent a month in hospital after being admitted with a recurrent lung infection.

His wife Graca Machel said Thursday that while occasionally Mandela has been uncomfortable, he has seldom been in pain.

Mandela's grandson has meanwhile thrust the increasingly acerbic family feud over the gravesites firmly into the public eye.

Mandla Mandela launched a tirade at close family members who took him to court to force him to reinter Mandela's children at the revered former South African leader's proposed burial ground in Qunu, his childhood village.

Mandla, who had moved the graves from Qunu to his own nearby homestead in Mvezo two years ago without the family's permission, accused one of his brothers of impregnating his wife and said others were born out of wedlock.

He also accused other close relatives of money-grabbing, and said Mandela's daughter Makaziwe was trying to "sow divisions and destruction" in her family.

The anti-apartheid hero's ex-wife Winnie, who has regularly visited him in hospital, "has no business in the matters of the Mandelas," Mandla added.

He also lashed out at his own brother Ndaba for claiming he was born out of wedlock.

"I don't want to hang out our dirty linen as a family in public but he knows very well that my father impregnated a married woman of which he is the result of that act.... As for the remaining of my two brothers we all know that they are not my father's children."

The three bodies were reburied Thursday in Qunu, but the fall-out from the dispute continued to reverberate.

South African Nobel peace laureate Desmond Tutu pleaded with Mandela's family not to "besmirch" the former president's name.

"Please, please, please may we think not only of ourselves. It's like spitting in Madiba's face," said Tutu in a statement, using Mandela's clan name.

Presidential spokesman Maharaj also urged the family to solve the increasingly bitter dispute "amicably".

"It is regrettable that there is a dispute going on amongst family members and we'd like that dispute to be resolved as amicably and as soon as possible," he said. (AFP)