U.N. humanitarian chief Valerie Amos is in South Sudan to get a first-hand look at the human cost of the country's conflict.
Amos arrived Monday in the capital, Juba, and met with displaced families at a site where U.N. peacekeepers are protecting more than 20,000 civilians.
The U.N. says Amos will also meet with aid groups and government officials during her three-day visit, and discuss ways to increase assistance to people in need. More than 500,000 South Sudanese have been driven from their homes since fighting erupted in mid-December.
South Sudan's government signed a ceasefire pact with anti-government representatives last Thursday in Ethiopia. Both sides have accused the other of violating the agreement, although no fighting was reported Monday.
The unrest began after President Kiir accused his former vice president, Riek Machar, of attempting a coup -- a charge Machar has denied.
Thousands are believed to have died in the fighting -- some in clashes between the army and rebel forces, others in targeted ethnic violence.