Fresh clashes in the tense boundary region between northern and southern Sudan have killed more than 70 people and wounded 120 others since Saturday.
Officials say fighters from the Misseriya, a tribe of Arab nomads, clashed with the former southern Sudanese rebel group, the Sudan People's Liberation Army, or SPLA.
The former rebels' deputy chief of staff, General Hoth Mai, said 69 tribesmen and at least six southern soldiers were killed in the fighting. However, Misseriya leaders dispute that claim; they say 37 tribesmen were killed and 62 wounded.
Misseriya leaders say their fighters initiated the clash on Saturday, in retaliation for an attack last week by the SPLA in which at least one person was killed.
Tension has increased in the region as Sudan's northern-based ruling party and the former southern rebels argue over boundaries of the oil-rich Abyei area. The Sudanese government is believed to support the Misseriya.
Abyei's status was left unresolved in the peace deal reached in 2005 that ended 21 years of civil war between the north and the south.
Under that agreement, southern Sudan gained general autonomy and is scheduled to hold a referendum on secession in 2011.
The deal calls for northern and southern Sudan to divide oil wealth equally but the north has refused to give up parts of Abyei.
In October, southern ministers temporarily withdrew from Sudan's national government to protest what they called the north's failure to implement key parts of the peace agreement.
The United Nations estimates that Sudan's north-south conflict killed more than two million people between 1983 and 2005.
Some information for this report was provided by AFP and Reuters.