"Greater care" should be taken to avoid casting doubt on the "accuracy and objectivity" of the Voice of America or creating the suspicion that "Project Truth" is a United States "propaganda" program, a commission reported to President Reagan yesterday.

It was an unintended coincidence that this language in a report by the United States Advisory Commission on Public Diplomacy contrasted yesterday with Reagan's pledge to expand U.S. information programs for spreading "the truth" about "the struggle between freedom and totalitarianism."

The advisory commission concurred in the need for "a bold new programming approach" in many areas of overseas information policy. The United States, the study noted, "has failed to accord the same significance to public diplomacy as have both its allies and adversaries."

While calling for a considerably greater American effort at all informational levels, however, the commission also cautioned about the special burdens that the U.S. International Communication Agency carries for maintaining the credibility and objectivity of American public diplomacy.

"Project Truth" was cited as an example of the dilemma. Initiated by this administration under USICA Director Charles Z. Wick, "to refute misleading Soviet propaganda and misinformation," it created suspicion that the communication agency itself "is engaging in propaganda," the report said.

The review commission said that it believed that suspicion "to be false," but recommended against further use of the "Project Truth" terminology. It did not suggest a specific alternative.

The commission similarly said it had found no evidence that the quality or the integrity of Voice of America broadcasts had been compromised, but urged caution "to avoid actions and policies that can be easily misinterpreted and cast doubt on VOA's commitment to accuracy and objectivity."

In describing the Fulbright Program of international educational exchanges "as among the most effective tools of public diplomacy" and recommending "that they be materially strengthened," the advisory commission report put considerably greater weight on their value than do many administration officials.

Along with "Project Truth," another major innovation of the information program under Wick has been the use of satellites to reach foreign television audiences. The advisory commission welcomed "these promising developments" in general, but questioned the funding of the most publicized and controversial of these programs, entitled "Let Poland Be Poland."

USICA proudly reported its estimate that 184 million people overseas viewed this program, on which 13 foreign heads of government appeared.

The advisory commission, however, noting that private organizations and groups contributed "nearly $500,000" to the program's production costs, expressed concern about creating a troublesome precedent. Programs "used to articulate major statements of U.S. foreign policy," it said, "ought to be financed with appropriated funds," not contributions.

Among the panel's other recommendations were consideration of resuming VOA broadcasting to Western Europe and designating the USICA director a statutory adviser to the National Security Council.

One unusual recommendation was that the president and Congress assure "the independence, continuity, genuine bipartisan character, and broad professional composition of the commission."

Informed sources noted considerable controversy behind the scenes about politically motivated changes in the advisory commission. The Reagan administration is expected to replace all but two of its seven members.

That would leave only commission chairman Leonard L. Silverstein, a partner in the Washington law firm of Silverstein & Mullens, and Tom C. Korologos, vice president and director of legislative affairs for Timmons And Company Inc., of Washington. Both are Republicans.

Reagan has nominated Edwin J. Fuelner Jr., president of The Heritage Foundation, a conservative think tank, to the commission, where he is expected to replace Silverstein as chairman.