Mthatha - Three hearses have entered Mvezo chief Mandla Mandela's home, hours after a court ruling against him.
The gates were locked, but have now been forced open.
The remains of three of Nelson Mandela's children are being exhumed at Mandla Mandela's Mvezo home.
The latest development comes hours after the Eastern Cape High Court earlier upheld a decision ordering Madiba's grandson to return the remains to Qunu.
Officials from the sheriff's office were forced to use a pick axe to open the gates at Mandla Mandela's homestead.
Police vans and the hearses then entered.
The media has not been allowed to enter while the exhumations take place.
In 2011, Mandla Mandela had the remains exhumed in Qunu, and reburied in Mandela's birthplace of Mvezo.
An affidavit filed in the province's High court, has largely confirmed what is already known about Madiba’s health.
He is critically ill. It describes his condition as “perilous” which effectively amounts to the same thing.
It also confirms his breathing is being assisted by a machine.
The term "assisted" is important, as it does not mean Mandela is on full life support.
Meanwhile, Mandla's actions were described as "scandalous" and "vicious", by an Eastern Cape High Court judge on Wednesday.
In his ruling on the graves of the former president's three children, Judge Lusindiso Pakade ordered the sheriff of the court to exhume the graves at Mandla Mandela's property in Mvezo at 3pm and move them to the family farm in Qunu for reburial.
Mandla Mandela had been given the opportunity to be heard in court, but only raised "irrelevant issues", Judge Pakade said.
The judge said the Mvezo chief's application to have last week's court order overturned was directed at "prejudicing the applicants [the Mandela family] who have already got relief against the respondent [Mandla Mandela]".
Shortly after Wednesday's ruling, Mandla Mandela's lawyers launched another application to rescind the court order. This was confirmed by lawyers for both sides.
Mandla Mandela's legal team contend the graves could not be exhumed on Wednesday until the new court application was heard.
"The sheriff may not exhume the remains. If they are exhumed it will have been done unlawfully," a lawyer said.
The graves are those of Madiba's eldest son and Mandla Mandela's father, Makgatho Mandela, who died in 2005; Mandela's first daughter Makaziwe Mandela, who died as an infant in 1948; and Mandela's second son Madiba Thembekile, who died in a car accident in 1969.
The graves were moved to Mvezo from Qunu in 2011 without the knowledge and consent of the Mandela family.
Additional reporting Sapa