A bishop of the Anglican church has appealed to the United Nations to investigate what he says are credible reports of serious crimes committed by Sudanese troops in Southern Kordofan.

Reverend Andudu Adam Elnail, who recently fled his home in the Sudanese state, spoke to reporters in New York on Friday, describing “ethnic cleansing” taking place in Southern Kordofan where he says there is evidence of mass graves.

He urged the U.N. Security Council to bring an end to worsening aerial attacks that are killing civilians and to press Sudan's government to allow humanitarian agencies to bring food and medicine to those in need.

Human rights groups say as many as 200,000 Southern Kordofan residents have been displaced by fierce fighting between Sudanese forces and the local Nuba militiamen which broke out in early June.

Southern Kordofan, which is ethnically divided, lies along the border between Sudan and South Sudan. It remains a source of conflict between the Arab-dominated government in Khartoum and the Nuba who allied themselves with the south's Sudan People's Liberation Army in the decades-long Sudanese civil war.