There is "very clear evidence of humanitarian need" in North Korea, the top U.N. aid official has said during the first visit of its kind to the isolated country since 2011.
U.N. Humanitarian Chief Mark Lowcock arrived in the North Korean capital of Pyongyang on Monday.
He met Kim Yong Nam, the nominal head of state and president of the Presidium of the Supreme People's Assembly, on Wednesday, the North's state media said.
Lowcock posted a video online outlining his observations after travelling to several areas in the southwest of the country.
"One of the things we've seen is very clear evidence of humanitarian need here," he said in the video, posted to his official Twitter account and the U.N. website.
"More than half the children in rural areas, including the places we've been, have no clean water, contaminated water sources."
Although humanitarian supplies or operations are exempt under U.N. Security Council resolutions, U.N. officials have warned that international sanctions over North Korea's nuclear weapons and ballistic missile programmes are exacerbating humanitarian problems by slowing aid deliveries.
About 20 percent of children in North Korea suffer from malnutrition, highlighting the need for more funding for humanitarian aid, Lowcock said.
Access for humanitarian workers was improving, he said without elaborating, but he noted that funding was falling short.
The United Nations says it had to stop nutrition support for kindergartens in North Korea in November because of a lack of funds, and its "2018 Needs and Priorities Plan" for North Korea is 90 percent underfunded.
While visiting a hospital that is not supported by the United Nations, Lowcock said there were 140 tuberculosis patients but only enough drugs to treat 40 of them.
More than 10 million people, some 40 percent of the population of North Korea, need humanitarian assistance, the United Nations said in a statement.
Lowcock was also due to meet humanitarian agency representatives and people receiving assistance to get a better understanding of the humanitarian situation, the United Nations said.