From Journalist Isma'il Kushkush January 1, 2012 -- Updated 1040 GMT (1840 HKT) A worker lays out bags of grain at the Doro refugee camp about 26 miles from the border in South Sudan's Upper Nile state. About 6,000 fighters attacked the town of Pibor, a military official says The attack occurred despite the deployment of U.N. peacekeepers to the area Casualties are still being counted, the military official says Tensions in South Sudan's Jonglei state are inflamed by tribal fights over grazing lands Khartoum, Sudan (CNN) -- Thousands of fighters attacked the remote town of Pibor in South Sudan, even as the United Nations deployed peacekeeping troops to the area amid reports of an imminent attack, a military official said Sunday. Casualties were still being counted from Saturday's attack by 6,000 fighters, which occurred in a portion of the town that was beyond the reach of the peacekeepers, said Col. Philip Auger of the South Sudan army. Ethnic tensions in the South Sudan state of Jonglei have been inflamed by tribes fighting over grazing lands and water rights -- disagreements that have dissolved into a number of cattle raids during which women and children were abducted. The United Nations said it sent a battalion of peacekeepers to Pibor on Friday amid reports that fighters -- members of the Lou Nuer tribe -- were marching on Pibor, home to the Murle tribe. The attack on Pibor follows reports last week that Lou Nuer fighters raided the town of Lukangol, burning it to the ground and forcing thousands to flee toward Pibor. U.N. Secretary-General Ban Ki-moon called on the tribes last week to work with the government of South Sudan to find solutions. South Sudan's vice president, Riek Machar, is leading an initiative to bridge the differences between the Lou Nuer and Murle tribes, including encouraging the armed groups to disband and go home, the U.N. has said. The violence in Jonglei state is the latest to rock South Sudan, which officially gained its statehood in July after separating from the north. Fighting erupted between Sudan's army and South Sudan rebels in Southern Kordofan even before independence was formalized. The violence has since spread to other areas. Within a few months, refugee camps filled as fighting in the border states of Southern Kordofan and Blue Nile intensified, displacing an estimated 400,000 people, according to the United Nations and aid agencies, such as Medicins Sans Frontieres (MSF) or Doctors Without Borders. That, in addition to the crisis in the Darfur region -- where war broke out in 2003 -- qualifies Sudan as one of the world's largest humanitarian crises, according to the United Nations.