Heavily armed rebels have killed more than 100 people, including women and children, in a cattle raid in South Sudan's Jonglei state, local officials have said.
Kuol Manyang Juuk, the governor of Jonglei state, said on Sunday that 103 people died in the Friday clash in Akobo County.
Juuk said 17 of the attackers were killed and that 14 soldiers from South Sudan's military, the SPLA, who were accompanying the cattle-moving tribe also died. Northeastern Jonglei state has been wracked by massive bouts of tribal violence for years.
The United Nations says more than 2,600 violence-related deaths were reported in Jonglei from January 2011 to September 2012, and account for more than half of reported deaths in South Sudan.
Akobo County Commissioner Goi Joyul said the attack took place during a yearly migration in which members of the Lou Nuer ethnic group were driving cattle across the Sobat River.
The commissioner said survivors of the attack saw the assailants use rocket-propelled grenades in addition to machetes and spears "thus overwhelming an SPLA force accompanying the people".
Joyul said the attackers in Friday's violence are believed to be members of the rebel group led by David Yau Yau.
A former member of the South Sudanese army from the Murle ethnic group, Yau Yau launched a rebellion after failing to win a parliamentary seat in the Sudanese general elections in April 2010.
South Sudan has repeatedly accused Sudan of backing Yau Yau and airlifting weapons and supplies to remote corners of Jonglei. Khartoum denies providing any support to the rebel group.
The International Committee of the Red Cross said it sent a surgical team to Akobo to help treat those injured in the attack.
In November, the aid group Doctors Without Borders said the increasing level of violence in Jonglei was causing a humanitarian emergency.
The group said health facilities are being targeted in the violence caused by inter-communal cattle rustling, fighting between government and rebels and a government disarmament process.
Joyul also confirmed "hundreds of families" were still missing.
"The attackers left with cattle and hundreds of children and women who have not reported back to the village," he said, explaining that some 3,000 people in all had been moving with their cattle when they came under attack.
"The army is trying to retrieve the cattle from the criminals, and that will not be easy," he said.