AFTER HOURS OF impassioned testimony by combat veterans, a congressman, a psychologist and others, the Commission of Fine Arts voted unanimously yesterday to place an American flag and military statue in an entryway plaza about 120 feet to the side of the Vietnam Veterans Memorial.

The commission, charged with guiding the development of Washington's federal architecture, rejected a plan favored by Interior Secretary James Watt and some veterans to place the flag near the center of the controversial, V-shaped memorial and the statue directly in front of it. A third plan, put forward by the American Institute of Architects, was also rejected.

The entryway plan also must be approved by the National Capital Planning Commission, which meets March 3. Watt, the third required approving party under the memorial legislation, already has approved all three options.

"This would be the front door, the overture" to the memorial, said commission Chairman J. Carter Brown in explaining the plan. He said it would give "maximum prominence" to the American flag, which would be clearly visible from the memorial wall and would form a "rallying point" for visitors.

Brown said the statue of three combat soldiers by Washington sculptor Frederick Hart would appear more impressive in the approved plan, which would place it in the "scale-giving context" of a copse of trees, but still visible from the memorial wall. In the rejected plan, he said, the statue would be standing alone in the field in front of the wall, competing for attention with it.

The flag and statue were added to the memorial site last spring as a compromise between the Vietnam Veterans Memorial Fund (VVMF), which raised private funds to build the memorial designed by Maya Ying Lin, and those who thought the Lin design unheroic and an insult to Vietnam veterans. But it was never clear where these elements were to be placed.

In yesterday's testimony, the battle over placement continued until the commission's deciding vote.

"This baloney has gone on long enough," said Jan C. Scruggs, head of the Memorial Fund. Scruggs, who conceived the memorial and led the effort to get it designed and built, said he favored the entryway concept.

He attacked those who opposed it, particularly veteran Milton Copulos, who testified yesterday that a poll of veterans taken at last November's memorial dedication showed that 74 percent favored the plan that would place the flagpole more prominently.

Scruggs said his organization had the poll "professionally evaluated by polling consultants and it has been found to be seriously flawed." Scruggs said the poll could not be considered to accurately reflect the views of veterans.

Rep. Duncan Hunter (R-Calif.), a Vietnam veteran, predicted the way the commission would vote and warned, "There will be veterans who will feel they have been betrayed because the word went out from East Coast to West Coast that the flag would be placed at the apex" of the memorial.

Hunter said that at the meeting last March, which produced the compromise agreement on the flag and statue, the entryway plan was "voted down." He then produced an old press release from Sen. John Warner (R-Va.), a supporter of the memorial from the beginning, that said the compromise decision was to place the flag above the memorial and the statue in front.

He said the press release also implied that the Commission of Fine Arts had approved this placement.

At this, Chairman Brown retorted, "That the Commission of Fine Arts was a party to any such compromise is simply an error." Brown said he was glad the country is governed "by laws and not press releases."

Robert Doubek, Scruggs' deputy on the Memorial Fund, then testified that both the press release and Hunter were in error. Doubek said the VVMF "agreed to present" the various plans, but didn't agree to support only one of them.

Last October, the VVMF supported the plan to put the flagpole above the memorial. But the commission found this plan unsatisfactory, and yesterday fund representatives returned to support the entryway plan with testimony from architects and others.

Sculptor Hart testified in favor of the entryway plan, saying it succeeds in "both preserving the integrity of the original design, while at the same time unifying all of the elements into a single memorial statement."

Representatives from the Veterans of Foreign Wars, AMVETS, Vietnam Veterans of America and other groups also testified for the entryway plan. Cooper T. Holt, executive director of the VFW's Washington office, said the plan is better "because of the prominent location of the American flag . . . because the sculpture is displayed in a setting doing full justice to its own power, and because the contemplative atmosphere created by the highly polished walls is uninterrupted."

Former representative Don Bailey, a Pennsylvania Democrat who last December got a bill through the House opposing the entryway concept, testified yesterday that the placement of the flag and statue sends a political message. "The struggle over the issue of message is not over," he warned yesterday. "It is not over."

Thomas Carhart testified that he was a veteran whose comrades died in his arms. "If we could hear from those men and women who died, where would they want that flag?" he asked. Then he answered his own question: "Right on top! Not hidden off in the trees somewhere."

For every combat veteran opposing the entryway plan, there were others approving it.

Harry G. Robinson III, an Army engineer officer in Vietnam and now dean of the Howard University School of Architecture and Planning, said placing the sculpture closer to the wall "would impose its imagery upon the visitor's experience and weaken the impact . . ." And a flag above the memorial "would be an intrusion into the tranquil horizontal space of the meadow and the awe-inspiring quality of the wall."

Steven M. Silver, a Veterans Administration psychologist and specialist in the so-called Vietnam stress syndrome, said his staff regularly brings troubled Vietnam veterans to the memorial to help them work out their buried torments. The memorial "does not impose a concept upon the viewer . . ." he said. "To impose figures in front of or atop the memorial would" restrict the viewer's emotional response.

Near the end of the hearing, commission member Alan R. Novak said he thought it had been "less raucous" than previous hearings on the memorial. He said the memorial itself may have exerted some calming influence on everyone. "The memorial is an enormous success," he said. "It doesn't matter how often you go, you're always overwhelmed by it."