South Sudanese politicians walked out of negotiations with the north over the weekend, accusing Khartoum of arming militias in the contested Abyei border region and provoking other fighting in a plot to overthrow the southern government.
The accusations and the breakdown in talks reignited fears for the stability of the oil-producing state less than four months before the south is due formally to secede on July 9.
Just short of 99 percent of southern voters chose to declare independence in a January referendum — a vote promised in a 2005 peace deal that ended decades of north-south civil war.
A return to full fighting would have a devastating impact on the region — Sudan borders fractured Libya and Egypt to the north and, among others, Kenya, Ethiopia and Uganda to the south.
The United States, Britain and Norway, who formed a troika to support the 2005 accord, issued a joint statement saying they were seriously concerned about the suspension of talks on preparations for the secession.
“We call upon the parties to take immediate measures to restrain armed groups under their influence,” they said.
More than 100 people died in clashes between north and south-linked groups in the central, fertile Abyei region — claimed by both sides — earlier this month, said the south.
On Saturday militias attacked Malakal, the capital of south Sudan’s Upper Nile state, and killed at least 42 people, the southern army that defended the town said.
Southern government minister Pagan Amum accused Khartoum on Saturday of arming militias in both those attacks and other recent clashes in the south.
Khartoum dismissed the accusation and says the south has sent troops into Abyei disguised as police officers. Abyei is supposed to be patrolled only by joint north-south army and police units.
African Union chairman Jean Ping released a statement calling the violence and Abyei border tension “disturbing” and said both sides should return to talks.
Before the weekend, the north’s ruling National Congress Party (NCP) and the south’s Sudan People’s Liberation Movement (SPLM) had been making slow progress in talks on issues like the position of their border, and how to divide debts and assets after the split.