The Voice of America should function as "a propaganda agency," comparable to an advertising agency selling soap, and it should portray the Soviet Union as "the last great predatory empire on earth," in the judgment of a new deputy program director for the overseas broadcasting agency.

These exhortations to "reverse the tendency toward mush that flowered in the previous administration," and abandon the contention that VOA is "a journalistic enterprise of some sort" with the standards of an Edward R. Murrow, were contained in a memo written on Sept. 21 by Philip Nicolaides, the new VOA coordinator for commentary and news analysis.

VOA Director James B. Conkling announced the Nicolaides appointment on Tuesday, along with two other appointments to high posts in the agency which has been riven by suspicions that the Reagan administration may be in the process of "politicizing" the organization.

Nicolaides' recommendations in the Sept. 21 report were in the form of a memo addressed to Conkling. It was written at a time when Nicolaides, a former Houston radio commentator and writer for conservative publications, was working in the offices of VOA's parent organization, the International Communications Agency, which is headed by Charles Z. Wick.

Wick and Conkling have denied adamantly that their organizations will engage in propaganda in any form. On the contrary, they have insisted, they will disseminate only "facts" and "demonstrable truths." Conkling last night, when informed that The Washington Post had obtained a copy of the Nicolaides memo, reiterated that "we are not a propaganda agency."

The Sept. 21 memo, Conkling said, was one of several documents that were "stolen from my office." As for its contents, Conkling said, "I didn't buy any of that," and Conkling said "that is not the reason I hired him."

"That was not written when he was with us," said Conkling, referring to the VOA. He said he encountered Nicolaides in ICA's headquarters, recognized him as someone he knew as an advertising agency writer some 30 years ago, knew he was "a good writer," and wanted Nicolaides to concentrate on subjects that "mirror the American way of life." A Nicolaides memo on that subject, Conkling said, "was stolen too." A spokesman in Wick's office said Nicolaides began work there on Aug. 3 in the public affairs office.

The memo from Nicolaides to Conkling, however, begins by saying, "In our recent discussions you reviewed a number of problems at VOA and asked me to come up with some considered recommendations. That's a tall order on a basis of my (admittedly) sketchy knowledge of VOA . . . ."

This wholly new dispute about the evolving policy of the ICA (soon to resume its earlier designation, U.S. Information Agency) and the Voice of America comes in the midst of escalating controversy about the direction in which the Reagan administration is headed in its information and educational-cultural exchange policies.

No document ever has come to public attention by someone on the public payroll which advocated so bluntly and militantly the outright use of the VOA as a blatant propaganda instrument. This is not to suggest that others may not have wanted to do so, particularly in the impassioned years of the Cold War. But the whole thrust of the VOA operation in recent years has been to champion news objectivity as its goal, which is how VOA's purposes as legislatively sanctified.

Nicolaides said, "our news should be factually accurate," although he proposed changing the law "in those cases where it is holding us back . . . ." He said, "credibility is all important. But we need not expatiate endlessly on stories which tend to put us or our allies in a bad light."

It is necessary to recognize, however, Nicolaides said, that "we are--as all the world understands--a propaganda agency. Propaganda is a species of the genus advertising . . ."

Thus, Nicolaides said, VOA's job involves "selling" and "selling involves more than reasoning, it involves emotions: people buy the sizzle not the steak" or "the protection against 'offending,' not a bar of soap."

In order to cope with the Soviet Union's "broadcast barrage" which is unrestrained by western standards of nicety, Nicolaides said:

"We must portray the Soviet Union as the last great predatory empire on earth, remorselessly enslaving its own diverse ethnic populations, crushing the legitimate aspirations of its captive nations, and ever seeking by all means, from subversion to miltitary intervention, to widen the areas it subjugates."

He specifically suggested efforts "to 'destabilize' the Soviet Union and its satellites by promoting disaffection between peoples and rulers, underscoring the lies and denials of rights, inefficient management of the economy, corruption, indifference to the real needs and wants of the people, suppression of cultural diversity, religious persecution, etc."

Scorning what he termed "the delusions of detente," Nicolaides said the Reagan administration can "attribute most of the blunders and shortcomings" of VOA "to previous administrations." If it toughens up its policy adequately, he said, the Reagan administration "can expect a barrage of charges that we're over-politicizing the VOA, losing credibility by slanting, reviving 'Cold War' attitudes! " But criticism coming from both sides, he said, "can be cited as proof that we are being even-handed."

"And when we finally get to the point that the only criticism of the VOA is howling from the Kremlin, antiphonal ululation from the U.S. hard left, and even greater Soviet efforts at jamming, we can crack open the champagne!"