South Africa has formally begun the process of withdrawing from the International Criminal Court (ICC), notifying the UN of its decision.
South Africa did not want to execute ICC arrest warrants which would lead to "regime change", a minister said.
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.
'Runaway train'
Justice Minister Michael Masutha said the Rome Statute, under which the ICC was set up, required the arrest of heads of state.
The consequence of this would be "regime change" and the statute was incompatible with South African legislation which gave heads of state diplomatic immunity, he said at a press conference.