The United Nations said that hundreds of people have been killed during recent tribal clashes and cattle raids in South Sudan.
The U.N. said Monday that 600 people were "reportedly" killed in fighting between the Murle and Lou Nuer communities in Jonglei state. A statement said there were unconfirmed reports of more than 750 people being wounded.
The U.N. representative in South Sudan, Hilde Johnson, said the cycle of violence must stop.
South Sudan ended a two-decade civil war with Sudan in 2005. It officially became Africa's 54th nation last month.
But the new country continues to struggle with internal violence, including cattle raids, a form of cultural and economic violence between tribes that is devastating communities.
The raising of cattle is a vital part of the indigenous economy.
On Sunday, South Sudanese officials said that more than 185 people have been killed in a recent cattle raid and an unrelated militia attack.
South Sudan army spokesman Col. Philip Aguer said fighters loyal to rebel leader George Athor crossed the border from north Sudan and attacked a town in South Sudan's Upper Nile state. Aguer said the violence which started Friday left 60 people dead, including seven soldiers and 53 militia members. He said the soldiers managed to repel the attackers.
Separately, South Sudanese officials said Sunday 125 people were killed in a cattle raid during which tribesmen stole 2,000 cattle in the country's east. Jonglei state Governor Kuol Manyang Juuk said eight villages were destroyed when warriors from the Murle tribe in Pidor county attacked the Lou-Nuer tribe of Uror county on Thursday.
Justice Minister John Luk Jok said he saw bodies strewn across the scene of the raid and that some children's limbs had been amputated.