A significant expansion of efforts to promote metropolitan Washington as a site for business relocation and growth is being planned by area leaders.

During a gathering of business and civic leaders here last night, officials of the Metropolitan Washington Board of Trade revealed details for a projected $96,000 promotion campaign that would build on a more modest effort started last January.

Called the "Case for Washington," an initial phase of the Board of Trade's program already has attracted more than 400 new jobs to the area as well as 152 inquires from interested business persons or investors about potential area ventures.

Airport displays have been installed at Dulles. National and Baltimore Washington airports and more than 8,500 packaged guides to the area have been handed to visiting business people staying at major hotels.

Of the 152 inquiries elicited by such promotions, the Board of Trade identified 33 serious prospects requiring staff work or contacts and 17 were concluded with decisions to relocate here or to invest in the D.C. area.

Board of Trade spokesmen said these additions to the D.C. area will mean $3.2 million in personal income. $1.7 million in new bank deposits, $1.4 million in new retail sales annually and seven more retail establishments.

Based on this record from "phase one," which cost $52,000, Board of Trade officials are seeking nearly $100,000 in contributions to support a second phase over the next year. Companies and institutions are being asked to donate either $500 or $2,000 each to underwrite:

Installation of airport displays promoting Washington at LaGuardia in New York, in addition to continued displays at airports in this region:

Advertising in the Eastern Air Lines shuttle magazine and production of a new audio-visual show on the Washington area:

An invitation-only program here next spring for 40 key real estate consultants and prospects from around the nation, who would be brought here for a one-and-a-half-day series of meetings and tours:

Direct mailings of "Case for Washington" booklets, local broadcast spots to make the case for Washington area residents and a general revision of informational materials.

Goals of the expanded program include an emphasis on corporate or regional headquarters, research and development organizations and internal business entities.

Several area counties also will continue to advertise and promote their own jurisdictions as well as participating in the overall program. The proposed $96,000 cost compares with the $150,000 spent annually by the Kansas City Chamber of Commerce and $350,000 annually by the Atlanta chamber for business development efforts.

David A. Edwards, executive director of Fairfax County's economic development authority, is new chairman of the Boarof Trade's area economic development committee.