The UN refugee Agency (UNHCR) on Tuesday said it was concerned about the rising number of South Sudanese fleeing into Sudan because of increased food insecurity caused by the ongoing conflict and deteriorating economic conditions, according to UN spokesman Stephane Dujarric.

"Heightened food insecurity and growing unrest in parts of South Sudan, especially in the northwestern States of Northern Bahr El Ghazal and Warrap, had resulted in the flight of some 38,000 people into East and South Darfur since the end of January," Dujarric said at a daily news briefing held here Tuesday. "UNHCR was concerned that the situation could worsen still as the nutrition situation in Upper Nile, Warrap and Northern Bahr Ghazal grew increasingly serious."

UNHCR urged more funding for clean water, sanitation and health services, food and shelter.

The majority of the people crossed into East Darfur, where an average of 500 South Sudanese -- or 100 households -- had been arriving per day, and the numbers kept rising last week, according to UN officials.

The situation "could quickly worsen as the nutrition situation in Upper Nile, Warrap, and Northern Bahr Ghazal grows increasingly serious," the UN agency said in a statement.

The arrivals are reaching Sudan in poor condition, according to the government of Sudan's Humanitarian Aid Commission. In addition to food, water and basic relief items, they need protection from sexual and gender-based violence, and many children have been separated from their families.

UNHCR is working with the UN Office for the Coordination of Humanitarian Affairs (OCHA) to respond to the needs, and is also advocating for direct access to East Darfur to support the response.

The UN agency also expressed concern about the 2016 South Sudan Regional Refugee Response Plan (RRRP) that covers the refugee programs in the neighboring countries, run by UNHCR and 39 partners. The Plan, which requires 1.3 billion U.S. dollars, is only 3 percent funded.

In South Darfur, more than 2,000 people were registered in Beliel Camp located in the village of that name. The South Sudanese coming to the camp "have faced insecurity en route" to the camp, many of whom are sick and in need of medical attention, according to UNHCR.

These groups are part of 2.8 million people throughout South Sudan who are officially classified as facing a food insecurity crisis or emergency, according to Fewsnet, the global body mandated to monitor such situations.

The food insecurity is worsened by the ongoing fighting in the world's youngest country, which started in December 2013 for political reasons, forcing 2.3 million people to flee their homes.