More than 31,000 houses were destroyed and about 17,000 families were left homeless, the U.N. said in a report Wednesday.
Meanwhile, North Korea's state media said Thursday that leader Kim Jong Il has sent a message to China's president, Hu Jintao, about the recent floods.
The World Food Program said the disaster has damaged some 30,000 hectares of arable land, leading to a potential loss of 100,000 metric tons of food - about 10 percent of the North's usual annual food shortfall.
However, the North Korean government has no plans to appeal for international help, the International Federation of Red Cross and Red Crescent Societies has said.
North Korea has relied on foreign donations to feed its people since disclosing in the mid-1990s that its state-run farm system had collapsed after decades of mismanagement and the loss of Soviet subsidies. Famine is believed to have killed 2 million people in the country, the AP reports.
The Seoul-based Good Friends group - an aid organization for North Korean refugees - said in a statement Wednesday about 3,000 people were dead or missing in the North after recent heavy rains. It didn't identify sources.