Each weekday at noon, Maria Lukojko, 77, ailing and single, descends from her tiny room in a shared apartment, rides two streetcars across town and, with the help of a heavy cane, mounts the marble stairs of a dilapidated 19th century housing block.

Although the journey has gotten more difficult in the past two years, it is a challenge on which Lukojko's livelihood has come to depend. Tucked away in the crumbling tenement is Warsaw's only free soup kitchen, and without its daily nourishment, Lukojko says, she would face a desperate struggle for economic survival.

"I can only say that I am very, very happy to be able to come here," she said at lunch in the mission, which is sponsored by the Roman Catholic Church.

A retired kindergarten teacher, Lukojko receives a pension equal to about $60 a month. "I have no other support," she said. "With the help of this, I can have enough food."

What is uncommon about Lukojko, social workers here say, is not her poverty but her access to one of the few private charities helping the homeless and impoverished in Poland.

Around her at the handsomely laid table, which serves up to 100 persons daily, were other equally grateful members of her luckless class: a young, mentally disturbed man rescued from a year of living in woods and foraging for mushrooms, an ex-convict with no job or home, and a 48-year-old disabled man who has an income of only $50 a month for himself and his ill wife.

Their daily gathering offers one view of a growing phenomenon of poverty in this economically crippled communist country. Recent academic studies based on official data suggest that at least 30 percent of Polish families now belong to an underclass unable to afford minimum daily necessities of food, shelter and services.

Most of these poor live somewhat better than those at the soup kitchen, but many may be worse off. Private social workers estimate that at least 2,000 homeless live in Warsaw's parks, alleys, and train stations. Official statistics show that nearly 10 percent of all elderly persons have monthly incomes of $35 or less.

Around Warsaw, the symbols of poverty usually associated with western capitalism are readily apparent. Older districts of the city contain whole blocks of state-owned apartments whose crumbling facades, broken doors and windows and tiny rooms -- without water service -- have the feel of a ghetto, although some are occupied by middle-income families.

Bedraggled men sell firewood and mushrooms collected from forests in city markets. Tourists in the picturesque old town have been approached by beggars.

Both the scale and the extremes of the material suffering are highly sensitive subjects in a country whose official ideology does not admit such problems. Official quarterly surveys of "the social minimum," as poverty is euphemistically known, are secret, and some academics specializing in the subject said they were advised to decline requests for interviews.

Until the Solidarity trade union broke down barriers to public discussion four years ago, the very existence of some kinds of poverty, such as homelessness, was neither acknowledged nor addressed by government officials.

"No society is interested in showing its dark side. But sometimes this goes too far," commented the trade union weekly Zwiazkowiec in a review of Poland's "embarrassing category" a year ago.

Despite such reserve, the government of Gen. Wojciech Jaruzelski recently has shown concern. Officials say the income problems have become particularly important because of public fears, reflected in polls, that economic changes introduced by Jaruzelski will increase disparities in workers' wages and create a permanent underclass of poor and unemployed.

Already, "there is a feeling of unfulfilled needs," said government pollster Stanislaw Kwiatkowski in a recent press conference, adding that the material position "for some . . . is constantly deteriorating and moving close to what is officially named as the social minimum."

A poll released by Kwiatkowski said the number of Poles defining their economic situation as "bad" or "very bad" doubled to 15 percent between October and December.

Studies by a group of economists at Warsaw University, based on the confidential official data, show even larger numbers of poor. In 1983, the studies showed, 38.5 percent of Polish working families and 52 percent of retired persons had incomes below the minimum amount defined by government officials as covering necessities. Members of the university team said at least 30 percent of all families were still below this official poverty line, and in some areas their numbers were increasing.

Other studies have shown that poverty tends to be concentrated among people living on pensions, young people in clerical and service jobs and large families. Income is not the only manifestation: More than one-third of young families live with relatives, because they have been unable to obtain their own housing.

In poor families, according to studies by the government economists, the share of family finances devoted to food has risen steadily since 1981 and now amounts to well over 50 percent. The diet, said government economist Teresa Pallaszewska Reindl, "is based on cereals and potatoes. There are no real hungry people, but there are a lot who have real limitations on their diets."

Poor workers can receive special benefits on a need basis from their factories or companies, and social workers at state-run medical stations are assigned to look after elderly and disabled persons. Government officials have promised an improvement this year in the pensions of poor retirees whose incomes have been devastated by inflation in recent years.

Yet the poorest of the poor, say social workers, frequently receive no help and almost no attention from the government. These are people not accounted for in social planning: unemployed workers, people who lose their homes, orphans and the handicapped forced out of overcrowded institutions and elderly people abandoned by the family members officially expected to take care of them.

At the church-operated Shelter of the Blessed Albert, a rude concrete home on the outskirts of Warsaw that is the capital's only shelter for the homeless, manager Stanislaw Wisniewski houses 20 men a night and said he covers only a fraction of the need. He said government health service specialists and police agreed with his estimate that at least 2,000 homeless, most of them hungry, live in Warsaw.

"There should be a home like this in every district of Warsaw -- they would all be filled," Wisniewski said. "These are the really lucky ones who are here. The others are on benches in the train station, in underground passages and garbage chutes."

Wisniewski's residents one recent snowy night included a young man "graduated" out of an orphan home. He said he had never been assigned an apartment in Warsaw and thus, under work rules, could not get a job. He had spent six months living in the streets.

An elderly man said he had been beaten repeatedly and forced to leave his apartment by his son-in-law. Police and other authorities simply returned him to the apartment, he said.

Wisniewski said that a recent appeal to the government by the religious society that runs the small shelters for the homeless in Warsaw and four other cities had prompted a reply from the director of social care of the Ministry of Health promising that "the problem of the homeless people of Warsaw will be solved." However, Wisniewski said, "until now, no one has been interested in the problem. Maybe nobody knew about it, because it was ignored by the authorities."