WASHINGTON (AP) _ Economic activity is refocusing to the suburbs as businesses relocate away from many city centers, a change that a new study predicts will have a major impact on metropolitan areas.

The automobile-oriented suburb, serving as a bedroom for city workers, is being succeeded by sprawling corporate and business centers, leaving inner- city residents without jobs or easy access to them, the report says.

The study, ''Suburban Business Centers: Employment Implications,'' was prepared for the Commerce Department by Truman A. Hartshorn of Georgia State University and Peter O. Miller of the University of Miami. The study was released by the Association of American Geographers.

The last two decades have seen major changes in suburbia, replacing the bedroom community with higher density areas offering increased economic and cultural opportunities, Miller and Hartshorn observed.

Now, they report, many suburban business centers have ''reached parity with the formerly dominant central business district of the central city.''

''Transportation investments, especially radial and circumferential interstate highways, have promoted the growth that has led to the development of major suburban business centers that now rival the central city's central business district,'' they reported.

But this development has magnified several problems between city and suburbs, particularly housing, employment and transportation differences.

Because many metropolitan areas do not have comprehensive, area-wide development programs, public policy fails to meet these needs, they said.

For example, many jobs have moved from central cities to these suburban centers but transportation systems remain focused on the automobile rather than the needs of many unskilled inner city residents looking for work.

Thus, Hartshorn and Miller observe, a dual pattern develops in which the affluent manager residing in a nearby suburb has a short car journey to work while the clerical or service worker must travel a great distance from the inner city or the rural fringe of the metropolitan area.

Solutions to this problem could include shared-ride taxis, loop buses, light rail systems or other means of getting people to work, they say. But the shift of housung and jobs to suburban areas means the large disadvantaged inner city populations are likely to face continuing erosion of their already weak economic position.

Continued funding of traditional rail and bus systems and lack of coordinated regional planning means ''the gap between the haves and have nots can therefore be expected to widen and become an increasing threat to the well-being of our metropolitan areas,'' they conclude.

While Hartshorn and Miller discussed urban-suburban problems in general, their report was based on detailed studies of six suburban business and economic centers in three metropolitan areas. Those are City Post Oak and the West Houston energy corridor at Houston; the Cumberland-Galleria and Perimeter Center-Georgia 400 centers at Atlanta and the King of Prussia suburban center in Montgomery County, Pa., and Cherry Hill in Camden County, N.J., both in the Philadelphia area.