U.N. tries to reach 60,000 fleeing South Sudan violence KHARTOUM (Reuters) - The United Nations said on Friday it was trying to reach some 60,000 people who have fled tribal violence in a remote area of South Sudan and urgently need food, shelter and medical assistance. South Sudan declared independence in July under a 2005 peace agreement with Khartoum that ended decades of civil war. But the new African nation has been struggling to end tribal and rebel violence that killed thousands last year. Fighting broke out last week between members of the Lou Nuer tribe and the rival Murle tribe. Some 6,000 armed Lou Nuer members attacked the town of Pibor in Jonglei state bordering north Sudan on Monday. U.N. sources said fighting had now almost died down after the army took control of Pibor but 60,000 people were now hiding in the bush or trying to return to their communities. "The government says this is a disaster and we make every effort to reach them," Lise Grande, U.N. humanitarian coordinator for South Sudan, told Reuters. We are concentrating on five locations of which four we can only reach by air. Three of these locations have been burned to the ground," she said. South Sudan Information Minister Barnaba Marial Benjamin said the number of casualties was still unclear because officials and aid workers had not reached all parts of the affected area. "So far, we have around 20 dead but we cannot say for sure because we need to assess first the situation on the ground," he said, adding that around 160 wounded were being treated in hospitals in the capital Juba. Doctor Without Borders (MSF), the only aid group active in the area, said last week it had suspended its work in the area after two of its clinics were damaged by fighting. Reporting by Ulf Laessing; Editing by Roger Atwood