''Fifteen percent is a huge famine,'' Mr. Natsios said in a telephone interview yesterday from his home in Washington. ''And the thing that's alarming is that those three provinces on the Chinese border where the survey was conducted are ones where the World Food Program has found that people are the best fed.''

Mr. Natsios, a former head of United States Government relief programs during famine crises in Africa, said that if these figures are reflective of the national picture, as many as half a million North Koreans may have died of starvation and famine-related illnesses in a population of about 22 million.

''Based on other reports we are getting, these findings seem to be an accurate and not exaggerated description,'' Mr. Natsios said, adding that food shortages would peak in November, when there should be a fall harvest -- although its size is hard to predict -- and a chance to plant winter crops.

Mr. Natsios, who visited North Korea in June, said the famine's effects were being worsened by the collapse of the national transportation system, which makes distribution of what food there is difficult.

World Vision, one of a handful of American-based private relief organizations working in North Korea, is recommending that Washington press China and Japan to give the North Koreans more food aid. Those organizations are also asking the secretive North Korean Government to allow relief experts and reporters to travel freely in the country, especially to remote areas. ''The North Korean Government must be pressed to open the country up so that we can judge its needs,'' Mr. Natsios said.