South Africa has formally begun the process of withdrawing from the International Criminal Court (ICC), media reports say.
They say diplomats have notified the UN of the move, accusing the ICC of bias against African countries.
Last year, South Africa refused to arrest Sudanese President Omar al-Bashir, who is wanted by the ICC on charges of genocide and war crimes.
He was attending an African Union summit in Johannesburg.
Mr Bashir denies allegations he committed atrocities in Sudan’s troubled western Darfur region.
Several media outlets say they have obtained a copy of the "Instrument of Withdrawal", signed by South Africa’s foreign minister.
"The Republic of South Africa has found that its obligations with respect to the peaceful resolution of conflicts at times are incompatible with the interpretation given by the International Criminal Court," the document says.
Neither South Africa nor the UN have officially confirmed the media reports.
There are also conflicting legal opinions as to whether South Africa can leave the ICC without parliamentary approval.
Human Rights Watch criticised the reported move.
"South Africa’s proposed withdrawal from the International Criminal Court shows startling disregard for justice from a country long seen as a global leader on accountability for victims of the gravest crimes," said Dewa Mavhinga, the NGO’s Africa division senior researcher.
"It’s important both for South Africa and the region that this runaway train be slowed down and South Africa’s hard-won legacy of standing with victims of mass atrocities be restored," Mr Mavhinga said.
Last week South African President Jacob Zuma met his Kenyan counterpart Uhuru Kenyatta, against whom an ICC prosecution failed.
Last year, South African warned it might leave the ICC.
The reported move to leave comes a week after President Zuma visited Kenya, a country that has been highly critical of the ICC ever since the prosecutor charged President Kenyatta with crimes against humanity.
He denied the charges, and the trial later collapsed due to lack of evidence.
Two weeks ago Burundi became the first country to express its intent to pull out of the ICC, a decision described by the court as "a setback in the fight against impunity".
Previously, the African Union has urged member states not to cooperate with the ICC, accusing it of bias against Africa.
The 124-member ICC opened in 2002. It is the first legal body with permanent international jurisdiction to prosecute genocide, crimes against humanity and war crimes.