|Brutal tit-for-tat cattle raids by rival ethnic groups remain common in areas of South Sudan [EPA]
South Sudan has accused the government of neighbouring Sudan of arming gunmen alleged to have killed dozens of people in a cattle raid, as the UN warned that tensions between the two sides risked regional peace.
"A militia group from Unity state penetrated into Warrap state... and attacked people in a cattle camp, killing over 40," Alison Manani Magaya, South Sudan's interior minister, said on Monday following the latest violence in the world's newest nation, which ceded from Sudan last year.
"This militia group was armed by the government of Khartoum," he added.
Magaya could not name the specific group responsible for the attack, which took place over the weekend, but claimed that rebel groups in Unity state were collaborating with one another.
"The number of wounded is still not clear, but they took a lot of cattle with them," he said, added that the gunmen were from the Nuer ethnic group, while those attacked were Dinka.
'Still counting the bodies'
"The situation in Sudan and South Sudan has reached a critical point"
- Ban Ki-moon, the United Nations chief
Magaya said government teams had been sent to investigate and that the death toll could rise as local officials "were still counting the bodies".
The UN has warned South Sudan faces massive challenges, as the world's newest nation struggles to support hundreds of thousands fleeing violence.
Ban Ki-moon, the United Nations chief, said on Sunday that tensions and a furious row over oil between the former enemies has become a major threat to regional peace and security.
"The situation in Sudan and South Sudan has reached a critical point. It has become a major threat to peace and security across the region," Ban told an African Union summit in the Ethiopian capital.
Key issues unresolved at independence have escalated into bitter arguments, including a row over pipeline transit fees to transport the landlocked South's oil to port in Sudan.
Juba said it had nearly completed a shutdown of its oil production, the fledgling nation's top revenue source, after it accused Khartoum of stealing oil worth $815m, and AU-mediated talks stalled.
South Sudan seceded peacefully from Sudan in July after decades of war, but both countries have since repeatedly exchanged allegations that each side backs proxy rebel forces against the other.
South Sudan was left awash with guns after years of conflict, and brutal tit-for-tat raids by rival ethnic groups to steal cattle from each other are common.
Last year, more than 350,000 people were forced from their homes due to violence, according to UN figures, while since June South Sudan has also taken in about 80,000 refugees fleeing civil war in north Sudan.