Gunmen have killed two African Union peacekeepers and critically wounded a third in Sudan's western Darfur region, the AU said Wednesday.
The peacekeeping mission said it was "deeply concerned" the gunmen were believed to belong to the Sudan Liberation Army, the rebel faction that signed the Darfur Peace Agreement in May 2006.
That signatories of the accord would attack peacekeepers is a severe blow to international attempts to promote the peace process and persuade other warring factions to join it.
The gunmen abducted and killed the two peacekeepers while they were "on administrative duty" Monday in the Darfur town of Graida, the AU said. "A third soldier was critically injured," the statement said, without giving details of how the attack was carried out.
"This deplorable and condemnable act was perpetrated by gunmen believed to be elements belonging to Sudan Liberation Movement or Army (Minni Minnawi faction), which is in full control of Graida," the statement said, referring to the leader of the SLA who signed the peace agreement.
In Addis Ababa, Ethiopia, where the African Union has its headquarters, an official said the slain peacekeepers were Nigerian.
"They were just shopping. They were unarmed and they were attacked by unidentified men," said Mahmoud Kane, the head of the African Union's Darfur Integrated Task Force.
With the 7,000-member AU force overwhelmed in a region the size of Texas, the U.N. Security Council last year recommended replacing it with more than 20,000 U.N. peacekeepers. The Sudanese government has rejected this, insisting the AU needs only technical assistance and equipment from the United Nations.
Also Monday, about 30 gunmen of groups that signed the May accord surrounded an office for the implementation of the peace agreement in El Fasher, the capital of North Darfur, and "threatened the officer-in-charge," the AU said.
The African Union is "deeply concerned that these, and other recent incidents of this nature, occurred in El Fasher and Graida, both of them strongholds of the signatories."
The AU said the slain peacekeepers' vehicle was stolen. It called on the Minnawi faction to investigate the attack and ensure the vehicle is returned.
More than 200,000 people have died and more than 2.5 million people have been displaced in four years of fighting in Darfur. The conflict began when members of the region's ethnic African tribes took up arms against what they saw as decades of neglect and discrimination by the Arab-dominated government in Khartoum.
The government is accused of unleashing a pro-government Arab militia that has committed many of the atrocities in the conflict.
Several rebel factions refused to sign the May accord, leading to an escalation in fighting.