The Greater Washington Board of Trade yesterday endorsed the D.C. government's overall plan for future downtown development, but urged that officials place greater emphasis on providing financial and tax incentives to businesses.

In its first formal response to a key element of the city's proposed comprehensive land-use plan, the board released a consultant's study that stressed the need for economic incentives downtown to preserve historical structures and attract theaters, hotels, retail shops and new housing.

"It should be the city's policy to use all workable incentives, frequently in combination with each other, to assure the feasibility of selected downtown preferred uses and mixed-use projects," said the report, which was prepared by the firm of Morton Hoffman and Company, Inc.

The consultant's study enthusiastically endorses the use a wide range of gimmicks, including federal and local investment tax credits, limited tax abatements, differential tax assessments for historical sites, and increased use of industrial revenue bonds.

The study also encourages the use of so-called density bonuses, which permit the size of new buildings to exceed legal limitations in exchange for the inclusion of certain public amenities.

"We found that you can do only so much to plan downtown development through regulations in a negative sense," said Robert Gladstone, chairman of the board's community development bureau. "It's still a tough ball game to encourage mixed use , but we're much more likely to get what we want in the city's downtown plan by applying some of these devices."

The study also concluded that the D.C. government agencies that oversee downtown development are fragmented and in need of improvement.

"As in other cities, the fragmented legal authority, dispersion of responsibility and lengthy revisions of development plans contribute to an unnecessarily long and expensive development approval process," the study said.

The consultant recommended that the city establish a public-private managment entity to coordinate downtown development, including implementation of the proposed downtown plan.

John (Skip) McKoy, director of the D.C. planning office, described the board's response as "very positive."

"It's slanted more towards asking us to focus more on incentives than disincentives for making things happen," McKoy said. "The report focused more on looking to tax and other financial incentives . . . to attract theaters and other developments that are less economically feasible than office buildings."

Mayor Marion Barry's Downtown Committee last summer released the proposed downtown development plan, which seeks to encourage a greater mix of construction downtown than simply office buildings.

The mayor's committee's plan largely coincides with the downtown element of the proposed comprehensive land-use plan that was released by the Office of Planning late next year and now is undergoing intensive public review.