David Shearer, Special Representative of the Secretary-General and Head of UNMISS, said they received reports over the weekend of clashes on supplies being transported by barge near Jikou area, in Upper Nile region forcing humanitarian workers to relocate out of the area for their own safety.
"These clashes in areas that have been relatively calm for many months is worrying," Shearer said in a statement issued in Juba.
He said the government and Sudan People's Liberation Movement-In-Opposition (SPLM-IO) led by former First Vice President Riek Machar have respected the ceasefire signed in 2018, adding that these latest inter-communal incidents raise tensions and increase the risk of sparking more serious violence.
Shearer observed that internal fighting within the ranks of an armed group in north-western Unity was also reported.
"The shortage of food and access to basic services in the wake of the civil war has put huge pressure on communities. The recent flooding has worsened this situation by destroying crops and pasture which will have a long-term impact on food availability in the coming months," he said.
UNMISS urged people not to turn to violence as a solution to the dire economic situation. The reconciliation and peace-building is the only viable path to development and ultimately, prosperity for all South Sudanese.
South Sudan descended into violence in December 2013, after President Salva Kiir sacked his deputy Riek Machar leading to fighting between soldiers loyal to the respective leaders.