The United States voiced concern Tuesday at the latest deadly inter-ethnic clashes in South Sudan, which it said had reached an "alarming" level of escalation.

Gunmen killed at least 51 people in the latest ethnic clashes in South Sudan`s troubled Jonglei state, the region`s governor said earlier in the day.

"The long-running cycle of violence between certain tribes, particularly the Murle and Lou Nuer, has escalated to an alarming series of revenge attacks in recent weeks, and we urge all sides to refrain from further provocative or retaliatory acts," National Security Council spokesman Tommy Vietor said.

Noting that the violence was "causing tremendous human suffering, displacement, and death," Vietor urged the South Sudanese government to respond and address root causes of the bloodshed.

"We urge the South Sudanese government to address the lack of security in these communities, and we urge the leaders of these communities to engage each other in a peaceful manner to come to a long-term resolution to the violence," he said.

Vietor also said Washington urged the United Nations "to provide any additional support that is needed by UNMISS (UN Mission in South Sudan) to carry out its responsibilities." 

Newly-independent South Sudan has declared Jonglei a national "disaster area" while the United Nations has launched a "massive emergency" operation to help over 60,000 people affected by the violence.

Last month an 8,000-strong tribal militia of Lou Nuer youths marched on Pibor, to exact revenge on the Murle people there for alleged attacks, abductions and cattle raiding. 

Jonglei, an isolated and swampy state about the size of Austria and Switzerland combined has limited mud roads often impassable for months during heavy rains.

Gun violence is common in the region devastated by two decades of war with northern Sudanese forces, a conflict that paved the way for the South`s independence last July.

The UN says that last year, violence between the two tribes left around 1,100 people dead and tens of thousands displaced in a series of cattle raids involving abductions of women and children.

Source: ANTARA