Juba , South Sudan ( CNN ) -- South Sudan 's army battled rebel forces Thursday , a military spokesman said , as negotiators from the warring sides prepared to meet for talks aimed at ending the violence that has pushed the world 's newest country toward civil war . Having sent delegations to the Ethiopian capital of Addis Ababa , the government and rebels are under mounting pressure from African and Western powers to reach a deal to stop clashes that have killed more than 1,000 people and displaced more than 190,000 . But there is no sign of an end of hostilities just yet . Military spokesman Col. Philip Aguer told CNN that military forces fought with rebels south of the flashpoint town of Bor , the scene of some of the heaviest fighting in the nearly three weeks of violence . He said the Sudan People 's Liberation Army was trying to stop the rebels from advancing on the capital , Juba , about 200 kilometers ( 124 miles ) away . South Sudan 's government tweeted late Wednesday : `` Our forces did a partial withdrawal from Bor but are still fighting in the suburbs # SouthSudan . '' President Salva Kiir on Wednesday declared a state of emergency for Unity state and for Jonglei state , of which Bor is the capital . The two delegations sent by Kiir and the rebels ' leader , former Vice President Riek Machar , are already in Addis Ababa . Talks were expected to begin Thursday but , as of early evening local time , had not . Not all parties have yet arrived in Addis Ababa , according to a representative of the Intergovernmental Authority on Development , an East African trade bloc which has been mediating in the conflict . However , it is expected all parties will arrive by Friday and formal talks should get under way , the representative , Tigist Hailu , told CNN . South Sudan 's neighbors , Western governments and the United Nations have been scrambling to stem the latest violence in the country , which seceded from Sudan in 2011 after decades of war . Hilde Johnson , who heads the U.N. mission to South Sudan , said she wanted to see both parties `` take a decisive step to cease all hostilities . '' `` We want to make this day the day that the violence stops , '' she said at a news conference in Juba on Wednesday . Humanitarian crisis . Kiir and Machar agreed Tuesday to send delegations to Addis Ababa , home of the African Union , for talks after violence in the oil-rich country that began on December 15 . A cessation of hostilities between their forces is expected to top the agenda . South Sudan 's government said Thursday via Twitter : `` We are participating in talks because we want peace for our people even though the rebel groups have not accepted a cessation of hostilities . '' Johnson said Wednesday it was too early to say if the planned talks were a breakthrough , `` but it is a step in the right direction . '' The spiraling violence has sparked a humanitarian crisis . An estimated 194,000 people have been displaced , with about 57,500 people sheltering in U.N. bases across the country , according to the United Nations Office for the Coordination of Humanitarian Affairs . Peacekeepers are working to protect the camps , but more resources are needed , Johnson said . She appealed for $ 166 million in aid to help provide families with food and other emergency relief . The U.N. Mission in South Sudan has voiced concern about what it said was mounting evidence of ethnic-based atrocities across the country . `` There has been killing and brutality ; we have seen killing on ethnic grounds . We need to do everything to prevent the cycle of violence , '' Johnson said , adding that the African Union had set up a a group to investigate human rights abuses . `` I condemn elements on both sides , '' she said . The Intergovernmental Authority on Development , an East African trade bloc that has been helping to mediate between the battling parties , has said an independent body is needed to monitor any cease-fire , Johnson said . Leaders of the bloc warned Friday that they would `` take action '' to stop the conflict if South Sudan 's warring factions did n't lay down their arms . Ethnic targeting . The fighting began in Juba but quickly spread across the country , with reports of mass killings soon emerging . Kiir , from South Sudan 's Dinka ethnic group , accused troops loyal to Machar , from the Nuer community , of trying to launch a coup . The two men have long been political rivals , and Kiir dismissed Machar , along with the Cabinet , in July . Kiir told CNN on Monday that African nations should have acted quickly to help quell the rebel forces . U.N. forces are patrolling the streets of Juba in order to protect civilians , Johnson said . CNN 's Khushbu Shah , Laura Smith-Spark , Arwa Damon and Yidnekachew Lem me contributed to this report .
NEW : Talks are expected to start Friday , representative of mediating bloc says . The army is battling rebel forces south of Bor , a military spokesman says . South Sudan 's president has declared a state of emergency in Unity and Jonglei states . A U.N envoy calls on warring parties to `` take a decisive step to cease all hostilities ''