Cattle are a vital part of the Sudanese indigenous economy, often becoming a motive for tribal clashes [EPA]

Nearly 60 members of rival tribes have been killed in disputes over livestock in South Sudan, officials said.

Fifty-eight bodies were found in two separate locations and a number of burnt tukuls, or huts, were identified, a United Nations spokesman told Reuters on Saturday.

The deaths were believed to be a result of clashes that broke out on Thursday between the Murle and Lou Nuer tribes in the Bier sub-county of the state of Jonglei, according to the UN and South Sudan government officials.

"There were several other locations that the UN has not been able to get to. We are relieved that calm appears to be prevailing," the spokesman said.

Kuol Manyang Juuk, the governor of Jonglei, gave a different figure, saying 38 bodies, including those of women and children, were found in Bier. Local media put the number of killed in the hundreds.

Juuk told the AFP news service further investigations could see the number of casualties rise as high as 50.

Murle tribe members were suspected of attacking five villages of the Lou Nuer tribe in Bier and burning down some homes, the governor told AFP.

"They have gone away with cattle. Some children were also abducted, and women," he said.

"It's known that Jonglei state tribes have been fighting [among] themselves and mainly for cattle."

The violence signals further instability in South Sudan, the world's youngest country, which gained independence on July 9.

South Sudan's government has accused the north of arming rival tribes and provoking insurgencies to undermine the region and keep control of its oil. Khartoum has denied the charge.

Ethnic groups in South Sudan have fought each other over cattle - a vital part of the indigenous economy - for centuries.

The numbers of casualties has increased in recent years after decades of civil war left the territory awash with small arms.

Between January and the end of June, 2,368 people have been killed in 330 violent incidents across South Sudan, according to UN data released in July.

Source: Agencies