The UN Office of Coordination of Humanitarian Affairs says a total of 101 thousand 415 individuals have so far crossed the border into South Sudan since the outbreak of fighting in Sudan on April 15.
OHCA says the significant majority of those crossing the border are South Sudanese returnees, while the remaining individuals are refugees and third-country nationals.
Most people have arrived in Upper Nile State, and others in Northern Bahr el Ghazal State, Unity State, Western Bahr el Ghazal State, and the Abyei Administrative Area.
It says a substantial proportion of the arrivals from Sudan are women and children.
OCHA added that humanitarian partners in South Sudan are scaling up their presence in key response areas and preparing an emergency response to address the needs of the most vulnerable people.