More than 120,000 people affected by the recent violence in South Sudan's Jonglei state may need emergency assistance – double the number of those originally thought to need help – the United Nations humanitarian official in the country said Friday.

Internally displaced women in South Sudan. [Gideon Pibor/UNMISS]

Fighting between Lou Nuer and Murle communities escalated sharply in late December, causing an estimated tens of thousands people to flee their homes in Pibor County and resulting in casualties, destruction of property and livelihoods.

Retaliatory attacks were then launched on communities in Akobo, Uror and Duk counties. The most recent attack took place on 16 January, when 80 people were reportedly killed and 300 houses burnt in Duk Padiet in Duk County, according to local authorities.

All concerned should redouble their efforts to put an immediate end to the cycle of violence, which is putting thousands of lives at risk and threatening the stability of the whole area

"The violence in Jonglei hasn't stopped," Lise Grande, the UN Humanitarian Coordinator for South Sudan, told a news conference in the capital, Juba.

"Only two weeks ago we launched a massive emergency operation to help 60,000 people. As a result of recent attacks, we now estimate that double that number will need help," she stated.

Yesterday the top UN envoy in South Sudan urged an immediate end to the cycle of ethnic violence in the newly independent nation, and called on the Government to hold the perpetrators to account and to deploy more forces to key areas to avert further bloodshed.

"The ongoing security crisis in Jonglei state is a test for all of us," said Hilde Johnson, the Secretary-General's Special Representative and head of the UN Mission in South Sudan (UNMISS).

"All concerned should redouble their efforts to put an immediate end to the cycle of violence, which is putting thousands of lives at risk and threatening the stability of the whole area," she added.

Humanitarian assistance is being provided in violence-affected areas and assessments are continuing, according to a news release issued by the UN Office for the Coordination of Humanitarian Affairs (OCHA).

A humanitarian response and coordination hub has been established in Pibor town and 15 aid groups are present on the ground, working to repair water points and provide food, household items, emergency education, nutrition, protection and medical assistance. Help is also being provided in Gumuruk, Likuangole, Boma and Walgak, and other villages will receive aid soon.

The recent spike in inter-communal violence has compounded an already difficult humanitarian situation in South Sudan, OCHA stated. Aid agencies were already supporting 30 simultaneous emergency operations before the crisis in Jonglei began.

Since mid-2011, tensions on the border with Sudan have also escalated, triggering fresh displacements. In May 2011, violence erupted in Abyei, displacing 110,000 people into Agok and South Sudan where they remain displaced.

In addition, ongoing conflict in South Kordofan and Blue Nile states in Sudan has caused approximately 80,000 people to flee into South Sudan since June 2011. Hundreds of new refugees continue to arrive every week.

"Operations in South Sudan are some of the most difficult and expensive in the region due to the combination of poor infrastructure and limited accessibility," said Ms. Grande, who is also Deputy Special Representative at UNMISS.

"It's a race against time every year to ensure that life-saving supplies are purchased and pre-positioned before the rains arrive. These attacks have occurred at the beginning of the dry season when stocks are at their lowest."

She stressed it is essential that the $763 million appeal for humanitarian work in South Sudan, covering 271 projects among 110 organizations, is adequately resourced early this year to ensure that assistance can be provided on time.