An "urban conservation policy" should be the keystone of federal efforts to stimulate economic growth, say District of Columbia officials preparing for a White House conference on economic policy.

Saying the District suffers "the whole range of urban crisis problems," they've recommended a series of mayor federal policy changes aimed at urban woes:

Higher investment tax credits in depressed areas and a shift in tax policy to favor rehabilitation of facilities over new construction.

A permanent local public works program.

Federal action to halt "redlining" or restriction of mortgage lending in urban areas, coupled with "greenlining" to favor such areas with added investment.

Direct subsidies to private business to hire and train disadvantaged and minority workers.

Halting the extension of urban services - such as public transportation - to exurban areas.

Revamping federal housing policy, with bigger housing subsidies tax incentives for housing rehabilitation and channeling Federal Housing Authority loan guarantees into central cities.

The recommendations, based on the needs of Washington but meant as national policies, were made by the municipal planning office in preparation for a public forum last night.

They are the city government's suggestions for discussion at White House Conference on Balanced Growth and Economic Development to be held here Jan. 29 to Feb. 2. Similiar priorities are to be developed by all states.

Citing the "spiraling public service costs" of building roads, sewers, schools and other facilities for sprawling suburbs, the recommendations says, "These trends must be reversed to restore economic health to the core cities of this land to protect the well-being of the entire nation."

Implicit in the District of Columbia government's proposal is a 180-degree turn in public policy away from programs that favor suburban development and back toward cities.

City officials call for halting sprawl by cutting off federal subsidies that encourage it, including transportation and sewer building aid, putting federal home loan guarantee programs, which now benefit suburbs almost exclusively, into cities and replacing tax advantages that favor construction of new plants in exurban areas with tax favors for rehabilitation.