At least 44 people were killed and more than 60 wounded in a rebel attack on Sunday in Jonglei.
Army spokesman Philip Aguer Panyang said rebels from David Yau Yau’s forces were responsible for the attack, The New York Times reported.
Acting Jonglei Governor Hussein Maar told AFP that UNMISS flew some of the injured people to Bor and Juba hospitals.
He added that the rebels, aided by Murle youths, stole thousands of cattle during the raid.
Last week, UNMISS Chief Hilde Johnson met President Salva Kiir Mayardit to discuss insecurity in Jonglei State.
Mr Yau Yau took up arms in 2010 after he lost the election for Jonglei’s Governor.