The D.C. Office of Planning has recommended approval of the Brookings Institution's controversial proposal to build a $25-million office and apartment complex extending into a residential neighborhood near Dupont Circle.

The plan must be approved by the city zoning commission, which began a series of public hearings on it yesterday.

Brookings' proposal has triggered a heated division among citizen activists in the Dupont Circle neighborhood who usually are united in their efforts to preserve the area's residential character.

Opponents, including the influential Dupont Circle Citizens Association, argue that the plan, if approved, would set a dangerous precedent that would provide incentives for further commercial development of the area's residential neighborhoods.

Supporters, including the area's Advisory Neighborhood Commission 2B (which approved the plan by a 5 to 4 vote), say the proposal will help stablize residential development along P Street NW, where part of the complex would be located, and that Brookings has made a major effort to work with community groups.

Brookings, a nonprofit public policy research center, is seeking the new building to generate additional income. It is asking the zoning commission to rezone for commercial use residential property it owns in the 1700 block of P Street NW, behind the present Brookings building at 1775 Massachusetts Ave. NW.

The property is now a vacant lot that is used mostly for parking by Brookings employes.

The overall plan calls for Brookings to construct an eight-story, L-shaped building that would include 100,000 square feet of office space and 69,000 square feet for apartments. The apartments would front on P Street NW.

D.C. planning director John H. McKoy said the city is committed to preserving Dupont Circle's residential character, but that the Brookings case is an exception. McKoy said among the decisive factors were Brookings' proposal to build 82 apartments units in addition to the office space and the building's tasteful design. In the present tight economy, McKoy said, it is unrealistic to expect developers to build only residential units, which generally are not as lucrative as office buildings.

He said the city wants in limited instances to provide adequate commercial space near downtown for businesses that cannot afford high rents in the more centralized downtown locations. McKoy added that the city also wants to accommodate expansion plans of institutions like Brookings as one way to keep such firms from moving to the suburbs.

James McGrath, the coordinator of several groups opposing the proposal, called the Brookings plan a "death-threat" to the Dupont Circle area's residential character. McGrath said if the Brookings proposal is approved, developers will use it to justify further rezonings for commercial development along P street NW and on other nearby residential streets.

"It's a devastating trend for residential housing," McGrath said, "and that block is right on the cutting edge."