A U.S. Conference of Mayors survey of homelessness and hunger in major cities shows that the demand for emergency shelter increased by 21 percent this year and the demand for food assistance went up by 18 percent despite improved economic conditions in most of the cities surveyed.

The annual report, released yesterday, showed that the District, with a 30 percent rise in requests for emergency shelter, had one of the highest increases in shelter demands of the 26 cities surveyed. No District figures were available on the requests for food.

The survey presented a two-sided picture of economic conditions in some cities.

While demands for food and shelter increased, officials in 16 of the cities surveyed said their cities had benefited from a national economic recovery and officials in half of the cities, including the District, said employment improved.

Some officials explained that while middle- and upper-income residents benefited from declining unemployment and urban renewal, the poor had more difficulty meeting basic needs because of higher housing costs and unemployment or low-paying jobs.

Boston Mayor Raymond L. Flynn, chairman of the task force that produced the report, said at a news conference yesterday that the survey results reveal a continuing human tragedy aggravated in part by federal government cutbacks in housing assistance, job training and food stamps.

"What is most tragic is that all this suffering is unnecessary in a nation as wealthy as ours," Flynn wrote in the report's cover letter. " . . . As a nation, we have no greater shame than the vast numbers of our fellow citizens who live on the streets, in alleyways, and in shelters."

Flynn called on the federal government to adopt a national housing policy to preserve existing housing stock.

He also recommended that Congress finance the Stewart B. McKinney Homeless Assistance Act at an "adequate level."

The bill authorized $412 million in homeless help for the current fiscal year, but the actual amount appropriated was $335 million.

The survey noted that more than one in five of the homeless people work full or part time and that shelters are seeing a growing number of young men between the ages of 18 and 25.

Almost half of the homeless population in the survey cities comprised single men and an average of 26 percent of the homeless people were severely mentally ill, the report said.

As noted in the previous year's survey, the fastest-growing homeless population continues to be families. Families demanding shelter increased by 32 percent this year and represented one-third of the homeless people in the cities surveyed.

The new survey shows that overall the demand for food and shelter this year rose at about the same rate as the previous year.

Researchers said that while the surveys publish percentage changes in the cities they do not include statistics on the actual number of homeless people because of variations in the reporting methods used by the cities.

Two-thirds of the cities reported turning away people who had requested food and nearly two-thirds reported that they had turned away people seeking shelter.

The District, which is barred by law from denying shelter to anyone who seeks it, has said that it does not turn away anyone.