JUBA, Jan. 21 (Xinhua) -- Thirty-seven humanitarian access incidents were reported in December in South Sudan with the majority occurring in Upper Nile, Jonglei and Central Equatoria, the UN humanitarian agency said on Monday.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said of these, 46 percent involved violence against humanitarian personnel and assets.

"The vast majority of total incidents (65 percent) occurred in Upper Nile, Jonglei and Central Equatoria," OCHA said in a report released in Juba.

According to the UN agency, the three counties that experienced the highest number of incidents - Rubkona, Maban, and Fangak - were largely related to bureaucratic impediments and threats, intimidation and harassment of staff.

"Ten incidents were significant in severity, involving ongoing bureaucratic impediments in the Sobat area, and conflict in Yei and Lainya which forced the suspension of humanitarian activities," OCHA said.

South Sudan has been embroiled in five years of conflict that has taken a devastating toll on the people, creating one of the fastest growing refugee crises in the world.

A peace deal signed in August 2015 between the rival leaders under UN pressure led to the establishment of a transitional unity government in April 2016, but was shattered by renewed fighting in July the same year.

The warring parties again signed the revitalized peace deal in the Ethiopian capital, Addis Ababa, in September last year amid international pressure to uphold the latest peace deal.