Christian Solidarity Worldwide (CSW) has added its voice to calls for an urgent investigation into human rights violations in Sudan's South Kordofan state.

It follows a leaked UN report into the human rights situation in South Kordofan accusing the government of Sudan of being complicit in the execution of suspected supporters of the ex-rebel Sudan People's Liberation Movement of the south and ethnic Nuba in Kadugli.

It also accuses the government of actively obstructing UN peacekeeping forces in Southern Kordofan following the outbreak of violence on June 5.

Sources cited in the report reveal the targeting of churches, congregations, and Nuban homes. Civilian areas are being bombarded on a daily basis and there are concerns that chemical substances are being used.

The report accuses both sides in the conflict of violating the terms of the 2005 Comprehensive Peace Agreement but states that the conduct of the Sudan Armed Forces (SAF) has been "especially egregious".

"Instead of distinguishing between civilians and combatants and accordingly directing their military operations only against military targets, the SAF and allied paramilitary forces have targeted members and supporters of the SPLM/A (Sudan People's Liberation Movement and Army), most of whom are Nubans and other dark skinned people," it states.

Northern forces stand accused of "violent and unlawful acts" against the UN peacekeeping forces, and the summary execution of a UN national staff member.

The report goes on to call for an independent investigation into violations of human rights and international laws in South Kordofan and recommends that perpetrators are brought before the International Criminal Court.

CSW’s Special Ambassador Stuart Windsor said the report was yet another confirmation of "appalling" human rights violations taking place in South Kordofan.

"Not for the first time the Sudanese regime has unleashed unspeakable violence against its own citizens in a manner that is at the very least comparable to the events that precipitated international action against the Gaddafi regime," he said.

"It is deeply worrying that the international response remains so muted, given mounting evidence of possible war crimes targeting a specific people group.

"CSW reiterates its appeal for immediate and robust international action to end the current violence, and fully endorses calls for an urgent international investigation into events in Southern Kordofan with a view to bringing identified perpetrators and planners of human rights abuses before the ICC."