While the showdown between the South Sudanese military and thousands of armed tribesmen over the flashpoint town of Pibor has subsided, the humanitarian situation in the area remains grim, a top United Nations official in the country warned on Tuesday.

Over the weekend, thousands of members of the Murle ethnic group who had sought refuge in Pibor in Jonglei state fled the town as it came under attack by a 6,000-strong column of armed youths from the rival Lou Nuer community, a UN report said.

"There is no doubt that there have been casualties," said Lise Grande, UN Deputy Humanitarian Coordinator for South Sudan, speaking to the press via teleconference from the national capital, Juba.

"I would put the number in the tens, perhaps the hundreds, but we don't know," she added, pointing out it was too early to confirm the overall number of deaths in and around Pibor.

Grande said peacekeepers serving with the UN Mission in South Sudan (UNMISS), supporting the Government, had rescued and evacuated civilians in Pibor and helped to deter further violence.

"The focus of the UN now is in tracking the column as it goes back and in providing emergency assistance to the people in Jonglei who need it the most."

Jonglei has been blighted by a series of reprisal attacks between the two communities, which have a history of animosity over grazing land, water sources and cattle raids during which women and children are often abducted.

Grande told reporters that as the Lou Nuer column had withdrawn from Pibor and was heading back to its own territory, tensions had subsided with many of the town's Murle inhabitants returning.

"The situation [in Pibor] is much more stable. We see this as a very positive step," she said, but also noted that while the security situation had improved, the humanitarian outlook was quickly deteriorating.

"The situation on the ground now, in humanitarian terms, is grim," Grande said, warning that there was "no question" that the returning inhabitants were in trouble. "They haven't had food. They haven't had access to clean water. And in a number of cases some of their people are wounded."

Pointing to humanitarian relief efforts, Grande said the UN World Food Programme (WFP) had flown in its first supplies of aid and distributed it to the most highly vulnerable – unaccompanied and orphaned children.

"Over the course of the next week," she continued, "WFP is going to be providing additional support."

She further noted that the UN Children's Fund (UNICEF), the UN High Commissioner for Refugees (UNHCR) and the International Organization for Migration (IOM) were also mounting a "massive emergency support programme" to help people as they returned.

Since the start of last year, more than 1,000 people are estimated to have been killed in South Sudan's ethnic clashes, with Jonglei one of the states worst affected by the violence. Thousands more civilians have been displaced from their homes.

Secretary-General Ban Ki-moon discussed the situation in Jonglei yesterday by telephone with South Sudanese President Salva Kiir, and commended his Government's efforts to resolve the ethnic tensions in the area.

Ban noted that the commitment to the rule of law and respect for human rights was fundamental. He also stressed the importance of addressing the root causes of the conflict.While the showdown between the South Sudanese military and thousands of armed tribesmen over the flashpoint town of Pibor has subsided, the humanitarian situation in the area remains grim, a top United Nations official in the country warned today.

Over the weekend, thousands of members of the Murle ethnic group who had sought refuge in Pibor in Jonglei state fled the town as it came under attack by a 6,000-strong column of armed youths from the rival Lou Nuer community.

"There is no doubt that there have been casualties," said Lise Grande, UN Deputy Humanitarian Coordinator for South Sudan, speaking to the press via teleconference from the national capital, Juba.

"I would put the number in the tens, perhaps the hundreds, but we don't know," she added, pointing out it was too early to confirm the overall number of deaths in and around Pibor.

Grande said peacekeepers serving with the UN Mission in South Sudan (UNMISS), supporting the Government, had rescued and evacuated civilians in Pibor and helped to deter further violence.

"The focus of the UN now is in tracking the column as it goes back and in providing emergency assistance to the people in Jonglei who need it the most."

Jonglei has been blighted by a series of reprisal attacks between the two communities, which have a history of animosity over grazing land, water sources and cattle raids during which women and children are often abducted.

Grande told reporters that as the Lou Nuer column had withdrawn from Pibor and was heading back to its own territory, tensions had subsided with many of the town's Murle inhabitants returning.

"The situation [in Pibor] is much more stable. We see this as a very positive step," she said, but also noted that while the security situation had improved, the humanitarian outlook was quickly deteriorating.

"The situation on the ground now, in humanitarian terms, is grim," Grande said, warning that there was "no question" that the returning inhabitants were in trouble. "They haven't had food. They haven't had access to clean water. And in a number of cases some of their people are wounded."

Pointing to humanitarian relief efforts,?Grande said the UN World Food Programme (WFP) had flown in its first supplies of aid and distributed it to the most highly vulnerable – unaccompanied and orphaned children.

"Over the course of the next week," she continued, "WFP is going to be providing additional support."

She further noted that the UN Children's Fund (UNICEF), the UN High Commissioner for Refugees (UNHCR) and the International Organization for Migration (IOM) were also mounting a "massive emergency support programme" to help people as they returned.

Since the start of last year, more than 1,000 people are estimated to have been killed in South Sudan's ethnic clashes, with Jonglei one of the states worst affected by the violence. Thousands more civilians have been displaced from their homes.

Secretary-General Ban Ki-moon discussed the situation in Jonglei on Monday by telephone with South Sudanese President Salva Kiir, and commended his Government's efforts to resolve the ethnic tensions in the area.

Ban noted that the commitment to the rule of law and respect for human rights was fundamental. He also stressed the importance of addressing the root causes of the conflict.