JUBA, May 23 (Xinhua) -- More than 20,000 South Sudanese have fled insecurity and hunger to Ethiopia as refugees since January, the UN humanitarian agency said Wednesday.

Citing the latest data, the UN Office for the Coordination of Humanitarian Affairs (OCHA) said registration figures of South Sudanese seeking safety and shelter in Ethiopia show the number of people who fled as refugees increased from nearly 419,000 in December 2017 to 440,000 as at the end of April 2018.

"The first quarter of 2018 has seen increased inter-communal violence and conflict affecting mostly Unity, Jonglei and Upper Nile," OCHA said in its monthly report released in Juba.

According to the UN agency, major drivers of the refugee outflow include growing insecurity and hunger.

"In Jonglei, fighting was reported in Akobo, Nyirol and Uror counties where several civilians were killed and thousands displaced," OCHA said.

It said an estimated 13,000 displaced people have arrived in Guiy village, north-west of Motot, following fighting in Nyirol and Uror counties.

"In April, renewed fighting in Mayom, Rubkona, Guit, Koch, Leer and Mayendit counties in Unity led to displacement of thousands of civilians," said OCHA.

Ethiopia is the second largest host of South Sudanese refugees after Uganda.

South Sudan descended into violence in December 2013 after political dispute between President Salva Kiir and his former deputy Riek Machar led to split within the SPLA, leaving soldiers to fight alongside ethnic lines.

The 2015 peace agreement to end the conflict was weakened after the outbreak of renewed fighting in July 2016.