The United Nations Human Rights Council on Wednesday set up a committee of three people to probe into human rights violations amid crisis in South Sudan.
The council agreed by consensus to set up the commission, with a renewable one-year mandate making a last minute amendment to a resolution to bolster scrutiny of the country.
South Sudan is charged with human rights abuses including gang rapes, destruction of villages and attacks on civilians that may constitute war crimes.
The country said it would cooperate with the council.
South Sudan's civil war erupted in December 2013 when President Salva Kiir accused his former deputy Riek Machar of planning a coup, setting off a cycle of retaliatory killings that have split the poverty-stricken, landlocked country along ethnic lines.
Tens of thousands of people have been killed and over two million forced from their homes, pushing the world's youngest nation to the brink of famine.
Over 2.8 million people - almost a quarter of the population - need aid, while in war zone northern areas 40,00 are being starved to death with aid blocked amid violence.