The United Nations humanitarian office says aid agencies need $166 million to save lives amid continuing violence in South Sudan.

Some 45,000 people have taken refuge in and around U.N. bases in the country and 81,000 people have fled their homes as a result of fighting that has raised fears of a civil war in the world's newest country.

The United States, Norway and Ethiopia are leading efforts to open peace talks between President Salva Kiir and the political rivals he accuses of mounting a coup.

Violence began spreading across South Sudan after a fight among the presidential guards on Dec. 15, pitting soldiers from Kiir's Dinka ethnic group against those from the Nuer ethnic group of former Vice President Riek Machar.

The U.N. is investigating reports of mass killings.