VATICAN CITY, FEB. 2 -- Asserting that one-fifth of the world's people are inadequately housed, the Vatican issued a strong call today for world action on the plight of the homeless, whom Pope John Paul II called "poorer than the poor."

Terming the issue one of "today's most serious questions," the document, prefaced by a letter from the pope, criticized land speculation, high rents, economic inequality and lack of concern by some societies and states -- none named.

In its sweep, the document clearly reflected the pope's concern about economic and social injustices around the world and their ethical implications -- a subject he always talks about in his travels.

The appeal for "urgent action" on providing homes for the homeless was contained in a 31-page document entitled, "What have you done to your homeless brother?" that was issued today by the Roman Catholic Church's Pontifical Commission for Justice and Peace.

"The church appeals to governments and to those with social responsibilities to make the necessary decisions and set up economic programs that will adequately meet the need for housing, particularly for the poorest," the document said.

Exactly how the crisis is to be eradicated it did not say, beyond calling on Catholics and people in positions of responsibility to address the issue as the church does, for example, in working through its local charities.

"This document isn't a blueprint for solving the problem," said Cardinal Roger Etchegaray, the French prelate who presided over the year-long study conducted to coincide with the 1987 U.N. Year of the Homeless. "This is an effort to wake up the human conscience to this problem. What we are trying to say here is that decent housing is a fundamental right of humankind."

The document called decent housing "a basic social good {that} cannot simply be considered a market commodity."

"In recent years," the pope wrote in his letter, "the housing problem has become dramatically more acute, because of population growth, especially in cities, or because of displacements due to work or because of the search for better living conditions."

"The effects are strikingly evident: the creation of megacities, the rise of zones around cities where living conditions are subhuman, marginalized, miserable," he said.