NAIROBI, Kenya — Systematic, brutal killings of hundreds of ethnic Nubians are being carried out by Sudanese forces loyal to President Omar al-Bashir's Khartoum regime, according reports from the toubled South Kordofan province.

The reports of widespread murders akin to ethnic cleansing and even genocide were confirmed by an international aid worker who recently left South Kordofan and who told GlobalPost of credible accounts of scores of Nubian men, who supported the south during the civil war, being killed by northern Sudanese troops.

“They were executed, sometimes with a bullet in the head but often their throats were cut. You are forced onto the ground, a knee put in your back, your head lifted up and your throat slit, just like a goat,” said the aid worker.

The aid worker, who has more than 20 years experience in Sudan, did not want to be identified for security reasons — fearing that his account might endanger the lives of his friends and colleagues still in South Kordofan — but his description sheds a light on a conflict that bears the hallmarks of Bashir’s genocidal war in Darfur, for which he has been indicted by the International Criminal Court (ICC).

Earlier this month the Anglican bishop of Kadugli, bishop of South Kordofan’s main city and the epicenter of the fighting, issued a stark warning of the ethnic violence and a plea for help.

“Once again we are facing the nightmare of genocide of our people in a final attempt to erase our culture and society from the face of the earth,” warned the Bishop Andudu Adam Elnail.

“It is not a war between armies that is being fought in our land, but the utter destruction of our way of life and our history, as demonstrated by the genocide of our neighbors and relatives in Darfur,” he said.

“This is a war of domination and eradication, at its core it is a war of terror by the government of Sudan against their people,” he said.

The violence in South Kordofan started on June 5 with an artillery barrage targeting the Kadugli home and office of the state’s most senior Sudan People’s Liberation Movement (SPLM) official.

The assault came soon after the departure of Ahmed Haroun, the state’s recently and controversially elected governor. Haroun, like Bashir, is wanted by the ICC for alleged war crimes committed in Darfur.

Northern soldiers backed by Antonov bombers and MiG fighter jets taking off from El Obeid airfield occupied parts of Kadugli city. Then, according to the aid worker, security forces went house to house dragging out opposition supporters, community leaders, intellectuals or anyone who was black.

The conflict is focussed on the Nuba Mountains in the center of Sudan. Once a highland refuge from Arab slavers, the mountains more recently were the redoubt of the Nuba SPLM during the 22-year civil war that ended with a 2005 peace deal that will see the south secede early next month.

The people of South Kordofan are northerners, except for the Nuba, who sided with the south during the civil war and who continue to protest their marginalization by Bashir’s Islamist regime in Khartoum.

Bashir says his forces are putting down a rebellion in South Kordofan. The Nuba say they are fighting for their survival.

The United Nations estimates that at least 73,000 have fled the fighting this month between Nuba fighters and the Sudanese army. With South Kordofan closed to outsiders no one knows how many have been killed, but reports of atrocities are trickling out.

Although impossible to confirm independently, reports from local residents say phosphorous bombs may have been used and there is talk of trucks loaded with young men being driven into the forest and returning hours later, empty.

A leaked U.N. report alleges that northern fighters masqueraded as Red Crescent workers to round up displaced people who were then marched away and other reports claim that civilians were executed outside the perimeter of the main U.N. base in Kadugli while peacekeepers cowered inside.

The aid worker told GlobalPost he thought “hundreds, possibly thousands” have already died.

“Its clear that anyone living in this area is fair game. Whether you’re carrying a hoe or an AK-47 you are the enemy because they know everyone in those areas voted for the Nuba SPLM,” he said.

He fears the current violence might outdo what he witnessed during the civil war.

“This is just the beginning. There is a huge concentration of troops, armored vehicles and tanks in Kadugli so it’s clear that intensive land attacks are planned, a full onslaught. This is going to be much worse than the last war,” he said.

He added that ethnically targeted killings had happened in the past, “but this is on a whole higher level of brutality, more of a planned operation.”

The aid worker hesitated at labelling the killing genocide, but said that what is going on is bad enough, whatever it is called.

“This is mass murder based on ethnicity and political affiliation undertaken in broad daylight in barbaric ways and it’s still going on,” he said. “I spoke to a Nubian friend yesterday, he asked me, ‘How many of us have to die before the international [community] will care?’”

Late on Tuesday, after more than three weeks of bloodshed, a deal was struck in Addis Ababa that called for northern-based soldiers of the Sudan People’s Liberation Army (SPLA) to be integrated into Khartoum’s army, offering a chance of peace in South Kordofan and Blue Nile state where thousands of SPLA fighters live.

However the announced deal did not include a ceasefire so, for now, the war goes on and the killing continues.