Officials of the Vietnam Veterans Memorial Fund yesterday unveiled a model of the statue of three American soldiers that they hope will become a part of the controversial memorial now being constructed on the Mall.

In a ceremony held in the cavernous interior atrium of the National Building Museum, John Wheeler, VVMF board chairman, hailed the statue as "a hopeful sign that our country can work together more creatively and in greater friendship after the Vietnam war."

The sculpture was created by Washington artist Frederick Hart in response to a compromise worked out by supporters and opponents of Maya Ying Lin's competition-winning design for the memorial. This compromise also called for the addition of a pole flying the flag of the United States.

Controversy concerning the proposed additions still continues, however. Before they can be built, the additions must receive approval of the Fine Arts Commission and the National Capital Planning Commission. Robert M. Lawrence, president of the American Institute of Architects, has mounted a campaign to oppose "any modifications" to the original plan and called the idea for a "trio of soldiers" an "intrusion" that will "cut the soul" out of Lin's design.

Lin was not present at the ceremony, but in a letter addressed to the VVMF she strongly protested the additions. Her original design for a long, angled wall of polished black granite containing the engraved names of nearly 58,000 dead and missing Americans in the war "needs no embellishment," she wrote. The concept of an "eloquent place" containing a "simple meeting of earth, sky and the remembered names, contains messages for all who will know that place," she said.

The contrast in style between Lin's abstract concept and Hart's sculpture could hardly be greater. Depicting three standing young soldiers (two white, one black) in battle dress, the sculpture is realistic, from open flak jackets to weapons to dog tags. In gesture and facial expression, especially, it is an impressive ensemble: The soldiers are portrayed at a telling moment, all the more intense because of its expectant ambiguity.

Charles Atherton, secretary of the Commission of Fine Arts, called the sculpture "a responsible and serious answer" to a difficult design challenge. But, as he also said, "The problem still remains where the sculpture is placed, if at all."

The Fine Arts Commission has not acted on the proposed additions other than to state, in an ambiguously worded letter from chairman J. Carter Brown to Interior Secretary James G. Watt, that "we believe it is possible to find a solution for adding those elements in such a way as to obtain approval" of the commission.

The proposal that will be submitted to the Fine Arts Commission on Oct. 13 locates the sculpture on relatively high, open ground slightly off-center and about 150 feet away from the angle of the granite walls. Hart foresees the final, bronze version of the figures to be slightly larger than life-size -- about 7 1/2 feet tall, set on a six-inch pedestal.

The proposed location for the 50-foot flagpole is slightly off-center and about 40 feet behind the granite walls. In addition to the emblems of the five military services that fought in Vietnam -- Army, Air Force, Navy, Marines and Coast Guard -- the base of the pole will carry the following inscription, according to the compromise proposal:

"This flag represents the gift of service to the American people by the veterans of the Vietnam war. Its presence at this site reaffirms the principles of freedom for which they fought. It flies continuously to honor their pride in having served our country under difficult circumstances."

Hart, a 38-year-old artist who for eight years has been working on a major series of stone statues for the west facade of the National Cathedral, was a partner (with Joseph Brown of EDAW Inc., an Alexandria architectural firm) in a design for the Vietnam War Memorial that won third place in the original competition.

Hart said the contrast of styles between his group of soldiers and Lin's wall is intended to "effect an interplay between image and metaphor . . . I see the wall as a kind of ocean, a sea of sacrifice that is overwhelming and nearly incomprehensible in its sweep of names. I place these figures upon the shore of that sea, gazing upon it, standing vigil before it, reflecting the human face of it, the human heart."

In contrast to the jury of artists and design professionals that selected Lin's design from the more than 1,400 entries to the memorial competition, the four-member panel that approved Hart's sculpture consisted entirely of Vietnam veterans: Milton R. Copulos, director of Energy Studies at the Heritage Foundation; William Jayne, deputy director of the Vietnam Veterans Leadership Program; Arthur C. Mosely, a real estate developer; and James Webb, author of "Fields of Fire," a book that was on the required reading list for entrants to the original competition.

Construction of the memorial is nearing completion on the site at the edge of Constitution Gardens near the Lincoln Memorial. VVMF president Jan Scruggs said yesterday that the memorial will be ready for the five-day National Salute to Vietnam Veterans scheduled to take place from Nov. 10 through 14, but the memorial will not be formally dedicated "until the statue is completed."

A scale model of the memorial, including the proposed additions, will be on view from 10 a.m. to 5 p.m. through Friday at the National Building Museum (the old Pension Building) at 440 G St. NW.