Rebels in South Sudan's Jonglei state have killed at least 24 soldiers, with several others missing or wounded, in the latest outbreak of violence in the troubled region, officials said Sunday.

The attack took place Thursday in the Pibor region of Jonglei after soldiers were sent to investigate sightings of rebel leader David Yau Yau, who split from South Sudan's army (SPLA) in April.

"There were 24 reported killed from the SPLA and 12 wounded, and there are about 17 missing," Jonglei governor Kuol Manyang told AFP, adding that it had taken time for the survivors to trek out from the remote area to report it.

"It was a small force that was sent to confirm that David Yau Yau was in the area... and then they were attacked by men in uniform joined by some armed civilians," Manyang said.

He suspected the civilians were made up of youths from the ethnic Murle group that live in Pibor County and to which Yau Yau belongs, and where he has reportedly been recruiting young people in recent weeks.