"More than 1,000 people died in Warrap in the past six months...there are a lot of people who want to go on and carry out revenge attacks for those that have died," UN special envoy David Shearer said, referring to the state in the north of the country.
The UN describes these attacks and killings as communal conflicts, adding that some 400 people have been abducted in eastern Jonglei state while hundreds died in fighting there.
Rival communities competing for land or carrying out cattle raiding leads to long cycles of revenge killings. The dry season will only see violence worsen, according to Shearer.
"The potential for conflict in Jonglei as a result ... is very, very high," said Shearer.
The special envoy called for dialogue between those fighting each other and said that UNMISS, the UN peacekeeping force in South Sudan, would deploy blue helmets to be temporarily based in trouble spots throughout the country.
South Sudan is still trying to emerge from six years of conflict that was formally ended when the power-sharing government was created in February.
