Displacement of low income people by middle class homebuyers who are reviving inner city neighborhoods is not a major national phenomenon, the Department of Housing and Urban Development said yesterday.

But HUD Assistant Secretary Donna E. Shalala, who released a preliminary study on the problem of people who are forced to move from their homes because of private development or public programs, said the government cares about their plight.

Noting many news reports of affluent people fixing up old neighborhoods, the HUD report said the "population and economic trends" represented by such efforts "are far too small to slow significantly or to reverse the movement to the suburbs and the loss of economic activity by central cities."

Shalala stressed that "we just don't have any hard numbers" on how many people are displaced by inner city revival, but she said that available studies have convinced HUD "that this is not a major national phenomenon with huge proportions of the total poverty population being involved.

"But for any individual who is being displaced -- whether in the District of Columbia or Los Angeles -- such an academic statement is irrelevant and sounds silly."

She said HUD does not want to create the impression that it "is not deeply concerned about involuntary moves" and added that within 45 days the department will recommend ways to cope with the problem.

Congress, in passing amendments to the Housing and Community Development Act last fall, ordered HUD to produce the recommendations by the end of last month, but the department found there is very little solid information on how much displacement exists or even how to define it, Shalala said.

The study cites Washington demographers George and Eunice Grier's definition of displacement as occurring when people are forced to move by conditions that affect their dwelling or neighborhood which they cannot control and which make continued occupancy "impossible, hazardous or unaffordable."

HUD said the definition "is not ideal, but it is useful.... It includes displacement due to reinvestment, disinvestment such as the refusal of banks to lend money in certain areas or the movement of stores out of those areas, abandonment, and the effects of public programs" such as highways or community development projects.

While reaching no conclusions of its own, the report said several recent studies have indicated that housing abandonment and disinvestment cause a much greater amount of displacement than activity by speculators or individual homebuyers.

The report also said that 20 percent of all households move each year and that according to the 1976 annual housing survey by the Census Bureau, fewer than 4 percent of all household moves -- involving some 541,000 people -- were "displacement moves."

Asked if inner city revival and its displacement of poor people had not increased since 1976, HUD officials said the studies it has examined do not indicate such an increase.

A 1978 study by the Griers indicated that fewer than 200 households in each of 15 cities surveyed were affected anualy by displacement due to middle-class investment activity, HUD said. George Grier said later the figure in Washington, D.C., may be 2,000 to 3,000.

The HUD report said, "Displacement as a direct result of government programs represents less than one-fifth of all displacement reported in the annual housing survey. The balance is reported to be the result of private sector activities."

It said that studies show "in-movers tend to be young white professionals, single or with small families and with sufficient income to overcome neighborhood deficiencies in schools, security, recreation and shopping, and who are attracted by the amenities of urban neighborhoods.

"Out-movers... are repeatedly reported to be elderly households, minority households and renters.

"Not enough is known about displaced households after their move to determine whether the majority are adversely affected by the change in housing location or whether they move to better units."

Shalala said that instead of undertaking a national study, the department will select 10 neighborhoods by mid-March for an in-depth look.

She stressed that HUD wants to encourage neighborhood revival. "We want to strengthen the tax base of the city and simultaneously protect poor people," she said.