A State Department advisory panel said yesterday that the United States should plan to accommodate a continuing and perhaps increasing flow of "boat people" fleeing from Vietnam in the months ahead.

Reporting on a 25-day trip through Asia to explore the Indochina refugee problem, the four-member panel endorsed "the general direction" of U.S. policies, and said that they are being implemented "effectively and humanely."

The study group stopped short of recommending how many future refugees the United States should accept. But it concluded that any major shift from current policies would "invite discord" among friendly countries, and recommended that "there should be no sudden, uncoordinated departures from current lines of action."

Retired diplomat Marshall Green said it is very important to "deal with the problem at its source" in Vietnam. However, he said the study panel did not meet with any officials of the Vietnamese government, with which the United States has no diplomatic relations.

The study panel did not comment on basic U.S. policy toward Indochina, but said that it was "repeatedly and forcibly struck" by the relationship between the political and military confrontation in the region and the flow of refugees. "Policies or actions which escalate conflict may well escalate refugee numbers," the panel said.

As recently announced by Secretary of State Alexander M. Haig Jr., U.S. policy seeks to isolate Vietnam politically and economically due to its occupation of Cambodia. The United States is also giving political support to Cambodian rebel forces fighting the Vietnamese.

The panel said it found "absolutely no grounds" for charges that the United States is seeking to continue the flow of refugees in order to destabilize the regime in Vietnam.

Regarding the legal status of the Indochinese refugees -- an increasingly controversial question in Congress and some segments of the executive branch -- the panel approved a "presumption" that all those who have fled to date are "refugees" in the meaning of U.S. law. While conceding that some have fled Vietnam largely for economic reasons, the panel viewed as crucial the fact that the Vietnamese government refuses to accept them back and that they would face persecution if they were able to return.

The Hmong people of the highlands of Laos are entitled to the same "presumption" that they are legitimate refugees, the panel said, but it expressed uncertainty about refugees from lowland Laos and Cambodia.

New York attorney Rita Hauser, a panel member, said a natural "pull factor" of attraction for a better life, sometimes spurred by letters from relatives who have resettled in the United States, is among the important reasons for the outflow. The panel recommended that broadcasts by the Voice of America be "balanced" in order to depict the hazards and difficulties of fleeing.

Hauser said that the U.S. resettlement program, costing more than $1 billion yearly, must be carefully studied in the light of a flow of people seeking refuge in this country from Poland, Central America and other areas.

Unless the United States and other western countries continue to be willing to accept the Indochinese refugees, "they may once again be pushed back to sea or across borders" by Asian countries unwilling to accept them, the panel said.

"This is a solution with which we cannot live in all conscience, bearing particularly in mind our deep pre-1975 involvement in Indochina and our association with many of those who are fleeing," the panel said.

Green, at a press conference on the panel report, said it is "a good question" without a ready answer how longlasting should be the American special obligation toward Vietnamese resulting from the heavy U.S. involvement in the 1960s and early 1970s.

In addition to Green and Hauser, the other members of the panel were James Greene, former deputy director of the Immigration and Naturalization Service, and Richard Wheeler, senior vice president of Citicorp.