JUBA, South Sudan - Negotiators from South Sudan's two warring sides arrived Wednesday in Ethiopia for peace talks, and a UN official urged both forces to bring the world's newest country "back from the brink."

Fighting continued in Bor, a gateway city to the capital of Juba, a government official said. Bor is just 120 kilometers (75 miles) from Juba.

Bor, the capital of Jonglei state, is the center of ethnically based violence stemming from the political rivalry between President Salva Kiir and ousted Vice President Riek Machar, the rebel leader accused of mounting a failed coup attempt.

Kiir declared a state of emergency Wednesday in Jonglei and Unity, two states where rebel forces have gained the upper hand in recent fighting.

Machar said Tuesday he would send his forces from Bor to Juba, but that threat was played down by Hilde Johnson, the UN representative in South Sudan.

"I think we need to take quotations with pinches of salt at this point of time," Johnson said.

"On January 1, the country is at a fork in the road, but it can still be saved from further major escalation of violence," she said.

Johnson urged Kiir and Machar to use the new talks to move toward peace, adding: "They can still pull the country back from the brink."

The fighting has killed more than 1,000 people, the UN says.

Pro-Machar forces in Bor appear to be taking defensive positions, Johnson said. The fighting in Bor has displaced about 60,000 people, making it the latest humanitarian crisis in South Sudan. The international Red Cross said the road from Bor to the nearby Awerial area was lined with people waiting for boats so they could cross the Nile River.

"There are tens of thousands of people here who literally picked up their kids and a few belongings and fled to the first safe place they could get to, which is Awerial," said David Nash, head of mission for Doctors Without Border. "They are camped out under trees with no sanitation and no safe drinking water."

Two teams of five negotiators each arrived in Addis Ababa, Ethiopia, and were expected to begin talks later Wednesday, said Getachew Reda, a spokesman for Ethiopia's prime minister.

The UN is "gravely concerned" about mounting evidence of gross violations of international human rights law, including the extra-judicial killings of civilians and captured soldiers, it said Tuesday. The UN's estimate of 1,000 dead was given days ago and the number of fatalities is believed to be higher as a result of the new fighting around the country, including in Bor.

South Sudan Foreign Minister Barnaba Marial Benjamin labeled Bor a war zone.

Government troops pulled out of parts of Bor because they were concerned about having to kill the "young boys" who fill the rebel ranks, one analyst said.

South Sudan's military "was told to withdraw," said Edmund Yakani, the executive director of the Juba-based group Community Empowerment for Progress, citing the accounts of contacts in Bor. "They communicated that these are young boys and we are killing them like nothing."

Government troops in Bor face renegade forces allied with a pro-Machar tribal militia known as the "White Army" because its young members of the Nuer tribe smear their faces with ash to keep insects away.

Johnson said that 240 UN police are to arrive later Wednesday in South Sudan to help police refugee camps. The UN says up to 180,000 people have been displaced internally by the violence, including about 68,000 at UN camps.

"Even with the tremendous efforts made by health partners, sanitation conditions are still inadequate largely due to the large number of people sheltering in United Nations bases, which have insufficient space to house these numbers," said Abdi Aden Mohammed, the World Health Organization's representative in South Sudan.

Kiir insists the fighting was sparked by a coup attempt mounted by soldiers loyal to Machar. But that account has been disputed by some officials of the ruling party, who say the violence began when presidential guards from Kiir's majority Dinka tribe tried to disarm guards from the Nuer ethnic group of Machar.

South Sudan has been plagued by ethnic tension and a power struggle within the ruling party that escalated after Kiir dismissed Machar as his vice president in July. Machar has criticized Kiir as a dictator and says he will contest the 2015 presidential election.

South Sudan peacefully broke away from Sudan in 2011 following a 2005 peace deal. Before that, the south fought decades of war with Sudan.