Juba , South Sudan ( CNN ) -- East African leaders on Friday gave South Sudan 's warring factions four days to lay down their arms after nearly two weeks of widening violence . If they do n't , the leaders of the Intergovernmental Authority on Development ( IGAD ) warned they 'll `` take action '' to stop the conflict that the United Nations says has killed more than 1,000 and forced some 121,000 from their homes . The warning came the same day the United Nations said the first of 5,500 additional peacekeepers had arrived in the country . The leaders of the IGAD did n't specify what sort of action would be taken . But a communique issued Friday in Nairobi , Kenya , appears to throw the group 's weight behind South Sudanese President Salva Kiir . In a joint statement by the leaders of the IGAD said they would not accept a violent overthrow of the country 's democratically elected government , and said any change must come through the democratic process . Kiir has accused rival politician Riek Machar , his former vice president , of trying to stage a coup . Machar has denied involvement in a coup . Fighting broke out between Kiir 's government and supporters of Machar on December 15 in the capital city of Juba . It quickly spread across the country , with reports of mass killings as evidenced by mass graves . Kiir and Machar are longtime rivals from two different tribal clans -- Kiir is from the Dinka tribe , Machar from the Neur . South Sudan 's government said it has agreed `` in principle '' to a cease-fire demanded by the IGAD , Information Minister Michael Makuei Lueth told CNN . Leith said Kiir 's government is open to `` unconditional dialogue '' to end the violence . The Intergovernmental Authority on Development appointed envoys from Kenya and Ethiopia to help broker a deal . Machar has n't responded to the proposal , leaving it unclear Friday what immediate impact the agreement would have on the fighting . The news of a possible deal comes as United Nations officials work feverishly to finalize details of sending peacekeeping reinforcements to South Sudan . The U.N. hopes to send them in no later than Saturday to help protect the 50,000 people now crowding U.N. bases , seeking shelter from the fighting . On Friday , 72 peacekeepers arrived in Juba , according to the United Nations . It was the first group of an additional 5,500 peacekeepers approved by U.N. Security Council . The additional personnel will increase the total peacekeeping force in South Sudan to 12,500 soldiers and 1,323 police officers . Meanwhile , U.N. officials and aid workers struggled to protect and provide food , shelter and medical care to those who have fled the fighting , which has spread to seven of South Sudan 's 10 states , according to the United Nations . More than 63,000 people have crowded on to U.N. bases in South Sudan seeking shelter from the violence , requiring a massive influx of aid . U.N. workers on Friday were able to resupply a U.N.-operated hospital in Malakal , U.N. Assistant Secretary-General Toby Lanzer said on Twitter . The U.N. Humanitarian Air Service also began flying in aid workers and supplies , he said . CNN 's Azadeh Ansari , Nana Karikari-apau , Moni Basu , Chelsea J. Carter in Atlanta , and journalist Kenneth Mijungu in Nairobi , Kenya , contributed to this report .
NEW : 72 of 5,500 new peacekeepers have arrived in South Sudan , the Group says . South Sudanese leaders tell South Sudan 's government , rebels to stop fighting or else . Group says it will take unspecified action if fighting does n't stop within Friday . South Sudan 's government says it 's ready to adopt a cease-fire .