A leaked UN report says war crimes may have been committed in the Sudanese region of South Kordofan.
The report accuses both sides of targeting civilians but it states that the government in Khartoum has been "egregious".
The oil-producing region borders the newly created nation of South Sudan.
It has seen intense fighting in recent months between the Sudanese army and local rebels.
The conflict has displaced some 70,000 people.
Al Jazeera's Kristen Saloomey reports from the UN headquarters in New York.
Source: Al Jazeera