Thursday's U.N. report said torrential rains caused severe damage to homes, public buildings, infrastructure and farms, affecting maize, soybean and rice fields. The worst-hit areas are Anju city and Songchon County in South Phyongan Province, as well as Chonnae County in Kangwon Province, where residents are in dire need of emergency food aid, it said.

Some 36,000 families in Anju do not have access to clean water; wells are contaminated due to overflow of pit latrines and open drainage, raising the risk of a diarrhea outbreak, the report said. A city official told The Associated Press earlier this week that it was the worst disaster in Anju's history.

North Korean officials are asking for food, fuel, medicine, water and purification supplies, while farmers are requesting seeds and fertilizer for the next season, the U.N. said.

Aid groups have donated emergency supplies, including the British-based charity ShelterBox, which dispatched 270 tents to North Korea, according to Howard Chang, a spokesman for Rotary International, who provides funding to ShelterBox.