Washington: The White House urged Sudan to "immediately" halt the escalation of "reprehensible" violence on southern Army positions less than a month before the south`s independence.
"The United States condemns reported acts of violence in Southern Kordofan that target individuals based on their ethnicity and political affiliation," White House spokesman Jay Carney on Friday said in calling for a ceasefire.
The statement was in response to reports of further attacks by northern forces on the Sudan People`s Liberation Army of the south.
President Barack Obama has sought to ensure the implementation of a Comprehensive Peace Agreement in Sudan and peace in Darfur.
He was instrumental in orchestrating the intense diplomatic effort backing a referendum that ultimately saw voters favour the south splitting from the north.
"The government of Sudan must prevent further escalation of this crisis by ceasing immediately its pursuit of a military solution to disarm the Sudan People`s Liberation Army in Southern Kordofan and to dissolve the Joint Integrated Units established under the Comprehensive Peace Agreement," Carney said in a lengthy statement.
"Accounts of security services and military forces detaining, and summarily executing local authorities, political rivals, medical personnel and others are reprehensible and could constitute war crimes or crimes against humanity."
Carney called on the United Nations to investigate the reports.
The perpetrators should "immediately halt these actions and be held accountable for their crimes”, he added.
Heavy clashes between Sudanese Armed Forces troops and northern members of the former southern rebel Army first erupted in South Kordofan on Sunday.
Carney said the violence threatened efforts to forge a durable peace between the largely Muslim north and the primarily Christian and animist south.
The heavily-armed state retains strong links to the south, especially among the indigenous Nuba peoples who fought on the side of the southern rebels, even though their homeland, the Nuba Mountains, is in the north.
Obama has signalled to the government in the north, under President Omar al-Bashir, that it could expect US incentives for choosing the path of peace.
That would include the lifting of economic sanctions and a process to remove US curbs imposed because Washington sees Khartoum as a state sponsor of terror.
The US President has dispatched a special envoy to Sudan, Princeton Lyman, to help resolve the crisis.
Washington is also working with the World Bank on whether to relieve Sudan`s debt, estimated at USD 38 billion. It is also considering nominating a full ambassador to Khartoum after July 09.