UN's Ban Ki-moon warns over South Sudan violations
23 December 2013 Last updated at 20:17 GMT
Allegations of rights violations in South Sudan will be investigated, and those responsible will be held to account, the UN secretary general says.
Ban Ki-moon urged leaders on both sides to find a political solution.
Tens of thousands of people have fled fighting, as rebels thought to support sacked former vice-president Riek Machar have seized major towns.