Nairobi - Troops from Sudan's north and south clashed on Wednesday in the disputed region of Abyei, as a southern military spokesman accused Khartoum of trying to expand the territory the north controls. Casualties were reported after the clash near what southerners call the Kiir River, but southern spokesman Col. Philip Aguer said he didn't immediately have an exact casualty toll. Abyei - a fertile land near oil fields - is the major flashpoint between the north and the south as the south prepares to secede and become the world's newest nation on 9 July. Aguer said the northern troops tried to cross the river on Wednesday. A UN spokeswoman said there were conflicting reports indicating that either northern troops or southern troops tried to cross. Violence has spiked ahead of the south's independence declaration, prompting US President Barack Obama on Tuesday to warn that leaders in the north and south "must live up to their responsibilities." Obama said the Khartoum-based government "must prevent a further escalation of this crisis by ceasing its military actions immediately, including aerial bombardments, forced displacements and campaigns of intimidation." Wednesday's fighting in Abyei came a day after the northern military bombed the north-south border region of South Kordofan, including at least one bomb that landed near a UN outpost. A UN spokeswoman, Hua Jiang, said 11 bombs were dropped in South Kordofan, five of which exploded. One bomb - caught in a vivid photograph - exploded near a UN airstrip. "There have been some artillery shellings and small arms firing near Kadugli town and certainly the fighting since is moving closer to our headquarters in Kadugli," she said. Jiang said 60,000 residents have been displaced by the violence, and that the UN is providing food and water to about 40,000 of them. However, the UN has been unable to fly in supplies for days. The UN refugee agency UNHCR accused Sudan on Tuesday of blocking aid deliveries in South Kordofan. UNHCR said north Sudanese authorities have for almost a week blocked planes from landing at Kadugli, about 100 kilometers north of the provisional border. Militias allied with the north have also set up roadblocks in Kadugli to stop overland access, it said. Jiang said Wednesday that a road was opened to the UN on Tuesday. She said the situation in the region remains "tense and unpredictable" but that there were not any reports of major clashes on Wednesday.
