Tension is mounting again in Sudan's oil-rich region of Abyei, following complaints from south Sudanese officials that northern troops have not withdrawn from the area. According to an agreement signed last month, both armies were to fully withdraw from Abyei by June 30 to avoid a repeat of the fighting in May that displaced tens of thousands of civilians. VOA Correspondent Alisha Ryu has details from our East Africa Bureau in Nairobi.  

Handout released by the United Nations Mission in Sudan (UNMIS) shows SPLA (Sudan People's Liberation Army) troops redeploying south from Abyei, 02 Jul 2008

The former rebel force of south Sudan, Sudan People's Liberation Army, also missed the end-of-June deadline to withdraw all of its troops from Abyei.

But the SPLA's Chief of Staff Oyay Ajak Deng tells VOA that while almost 90 percent of his soldiers have been moved out of Abyei town, government troops still remain there in full force.

"They should have started pulling out their forces on the 30th, but we are not seeing any movement on their side," said Deng. "Of course, we are very much concerned. Definitely, there is tension in the area. If they continue to remain there, of course, it will be complicating the matter again."

Abyei, which sits on rich oil fields straddling the north-south border, is claimed by both sides.  

Its disputed status has long threatened a fragile peace deal the rebels and Khartoum signed in 2005 to end more than two decades of civil war. An international boundary commission determined that Abyei belongs to the south. But Khartoum has refused to recognize the findings.  

In mid-May, fierce clashes between northern and southern troops in Abyei destroyed the town and sent as many as 100,000 people fleeing for safety. The fighting renewed fears that the two sides could slide back into a civil war.

Last month, the political arm of the SPLA and Khartoum's ruling National Congress Party drew up a road map for peace in Abyei, which included an agreement for a full military withdrawal and the deployment of a special joint unit of northern and southern troops and a new police force.

A battalion of 320 soldiers from the SPLA and 319 from Khartoum is in place. But the police force has not arrived and the joint unit cannot take full charge of security in Abyei until the military withdrawal is complete.

A special advisor to Sudan's Information and State Ministry, Rabie Abdul Arthi, says technical and logistical issues have delayed the withdrawal of northern troops from Abyei town. But he says the troops are moving out.

"According to the information that I am aware of, the withdrawal of government forces has started and within a few days, this withdrawal will be completed," said Arthi. "There is no difference between the two parties and the government is not insisting to keep troops in the Abyei area. This is not the situation."

The road map also calls for The Hague's Permanent Court for Arbitration to decide whether or not the Abyei boundary commission exceeded its mandate in its 2005 ruling.