(CNN) -- The United Nations is urging an investigation into alleged serious atrocities that it says could amount to crimes against humanity or war crimes in Sudan's Southern Kordofan state.
A recent report by the U.N. Office of the High Commissioner for Human Rights, based on human rights reports by the winding-down U.N. peacekeeping mission, describes arbitrary arrests, extrajudicial killings, alleged house-to-house searches and possible mass graves in the state, which borders both Sudan and the newly created country of South Sudan.
Since the start of the conflict on June 5 -- when fighting broke out in the state capital, Kadugli, between the Sudanese Armed Forces, or SAF, and the Sudan People's Liberation Army-North, or SPLA-N -- access to the area has been limited, preventing verification of the allegations.
"However what (the report) suggests has been happening in Southern Kordofan is so serious that it is essential there is an independent, thorough and objective inquiry with the aim of holding perpetrators to account," High Commissioner for Human Rights Navi Pillay said in a news release Monday.
Most of the alleged international law violations have been committed by the SAF, according to the report, against people affiliated with the SPLA-N and South Sudan's leading political party, the Sudan People's Liberation Movement.
The victims hail mainly from the Nuba tribe, a majority of which fought alongside the southern Sudanese rebels during Sudan's 22-year civil war that ended in 2005. During the conflict, the Khartoum government confined members of the tribe to "peace camps" and subjected them to human rights violations and killings that lasted until a 2003 cease-fire, according to accounts of the war.
"The SAF regularly conducted aerial bombardments in the Nuba Mountains, and in several towns and villages populated by the Nuba," states the report, which covers the period between June 5 and 30. It also describes widespread looting by a government-aligned militia, alleged burning of houses in Nuba villages, hindrance of humanitarian assistance and allegations of several mass graves in Kadugli and other villages.
A July report by the Satellite Sentinel Project, affiliated with actor George Clooney and human rights activist John Prendergast, claims to have found evidence of these graves, and "evidence consistent with a possible pile of people in body bags or white plastic tarps in Kadugli."
In addition, bombs were dropped near U.N. Mission in Sudan facilities, the U.N. report states, and Sudanese staff members, especially those of Nuba origin, were arbitrarily detained. It says the SAF closed down the town's airport on June 7 and prevented all civilian air traffic.
Military observers attempting to verify the existence of mass graves in the village of Murta on June 16 "were arrested, stripped of their clothes, and (it is) believed that they were about to be executed when a senior SAF officer intervened," according to a leaked U.N. Mission In Sudan human rights report.
The conflict has resulted in the displacement of more than 70,000 people in addition to the loss of lives and destruction of people's homes and churches, the United Nations said. Pillay also expressed concern about violence continuing since the report was compiled, and called for unhindered access for human rights monitors and humanitarian agencies.
The latest conflict was preceded by months of tension in Southern Kordofan. Gubernatorial elections were postponed before finally being held this May. However, the Sudan People's Liberation Movement refused to accept the election of Gov. Ahmed Haroun, who had been indicted by the International Criminal Court for war crimes and crimes against humanity in Darfur.