"He is in a permanent vegetative state and is assisted in breathing by a life support machine," said a legal filing related to a family dispute over reburying the remains of three of Mandela's children.
"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 document was presented to South Africa's Eastern Cape High Court as President Jacob Zuma reported that Mandela's health had faltered and cancelled a trip to Mozambique.
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The next day Zuma reported that Mandela's condition had "improved during the course of the night".
"He is much better today than he was when I saw him last night. The medical team continues to do a sterling job," Zuma said in a statement dated June 27.
Lawyers for Mandela's relatives, family members themselves and government officials were not immediately available for comment.