U.N. refugee agency officials say health problems tied to poor weather and lack of sanitation are acute among 170,000 Sudanese refugees living in camps and settlements across South Sudan's Unity and Upper Nile states.

The agency's chief medical officer, Dr. Paul Spiegel, described the situation as "quite alarming" with many refugees suffering from respiratory tract infections, diarrhea and malaria, and cholera becoming a serious threat.

Agency spokesman Adrian Edwards told reporters Friday in Geneva nearly half the Upper Nile refugees are younger than 11 and many have mothers or other caregivers too sick and weak to look after them.

He says nearly 1,600 children younger than five are severely malnourished in Yusuf Batil, a camp hosting 34,000 Sudanese from Blue Nile State.