A former Central Intelligence Agency officer charges that the Johnson administration and the CIA fabricated "evidence" in 1965 to help prove that the war in Vietnam was being fueled by outside arms and to set the stage for U.S. involvement.

The officer, Philip Liechty, now 41 years old, says he inadvertently came upon CIA documents early in his 15-year career with the agency that specifically described plans to provide such phony evidence.

Liechty, a specialist on Asia, eventually became a case officer handling secret missions in the CIA's top-secret Directorate for Operations. He contends he was fired in 1978 as a "dissonant voice" for complaining about the way the operations directorate was run and for charging that intelligence was being manipulated. The official explanation for his ouster, he says, is that it was part of a personnel cutback.

One set of documents that Liechty says he saw in the early 1960s involved a plan to take large amounts of communist-bloc arms that the CIA had collected and stored in warehouses, load them on a Vietnamese-style coastal boat, fake a firefight in which the boat would be sunk in shallow water and then call in western reporters to see the captured weapons as proof of outside aid to the Viet Cong.

The other documents involved an elaborate operation to print large numbers of postage stamps showing the Vietnamese shooting down a U.S. Army helicopter. Liechty says this was a highly professional job, and that the very professionalism required to produce the multicolor stamp was meant to indicate that it was produced by the North Vietnamese because the Viet Cong would not have had such capabilities.

Liechty claims that the CIA printed sheets of these stamps. Letters in Vietnamese were then written and mailed all over the world."And the CIA made sure journalists would get hold of them," he says.

If Liechty's claims are accurate, the CIA scored a major public relations coup because a full-color blow-up of the "North Vietnam Stamp" appeared as the cover of Life Magazine on Feb. 26, 1965, just two days before the Johnson administration published its famous "white paper" on the fighting in Vietnam called "Aggression From the North."

Liechty says that several sheets of the stamps were in the file that he saw and they were "all printed on CIA presses."

An account of a sighting on Feb. 16, 1965, of a "suspicious vessel . . .carefully camouflaged and moored just offshore along the coast of Phu Yen Province" in South Vietnam is also accorded considerable space in the Johnson administration's white paper.

The cargo vessel was "sunk in shallow water" after a reported attack by South Vietnamese forces. The vessel was reported to contain at least 100 tons of military supplies "almost all of communist origin, largely from Communist China and Czechoslovakia as well as North Vietnam." The white paper noted that "representatives of the free press visited the sunken North Vietnamese ship and viewed its cargo."

Liechty says he is obviously unable to produce the documents he says he saw more than 15 years ago, and that the plan suggested there were to be a number of these boat incidents without indicating dates. But he is personally convinced that the incident described in the white paper was one of those staged. "Everything matched perfectly," he says.

Publication of the white paper turned out to be a key event in documenting the support of North Vietnam and other communist countries in the fighting in the South and in preparing American public opinion for what was to follow very soon: the large-scale commitment of U.S. combat forces to the fighting.

Later events made it clear that North Vietnam was indeed heavily involved in the war in the South.

On March 6, 1965, just a week after the white paper was issued, President Johnson issued orders for two Marine Corps battalion landing teams to go to South Vietnam.

A spokesman for the CIA, Dale Peterson, said "it is not our policy to comment on such allegations" when asked about the validity of Liechty's claims.

Liechty joined the CIA in the summer of 1963. His first two years there were spent as an intelligence analyst in a part of the agency that searches CIA "Master 201 personality files" looking for what Liechty calls "derogatory or inflammatory information on individuals that other branches of government are seeking information about, possibly for a job opening."

"Our sole job was to report derogatory information on people," he says, and in over two years he says he handled about 5,000 files. In those days, he says, this was all done manually and information sometimes became misfiled because documents were not returned to their proper places.

"One day I pulled a file," Liechty says, "and there was a quarter-inch of documents inside relating to Vietnam operations. The top three or four pages were an operating plan of a new agency proposal to fabricate evidence of outside support of the Viet Cong effort in South Vietnam. This was no rough draft. It was a carbon copy of a final proposal and my recollection is that it was written in response to direction from the White House and could not have happened without President Johnson's approval."

Liechty claims that of all the documents he saw, he remembers two specific plans especially because of events that unfolded later on television and in newspapers and magazines.

"The one that shocked me most," he says, involved a plan to "take out of storage" tons of communist weapons, "buy a Vietnamese-style boat, phony a firefight, sink it in shallow water and call in the newsmen to see."

Liechty claims the CIA has warehouses filled with "hundreds of thousands of weapons and millions of rounds of ammunition" manufactured by many communist countries. These weapons were captured or acquired in a variety of ways, he says, and can be used to link almost any nation to a specific event by planting them at the scene.

The sunken-boat plan, he said, provided a perfect example to show arms flowing into South Vietnam from many countries.

At the time, Liechty says, Vietnam was still "a new subject" within the CIA and there was some "uneasiness" in general about what was going on. When he first saw the documents, he said he had "no idea where these guys were going."

But later, he said, it became "clear what they were doing. This was intended to con the Congress and the American people." It was supposed "to support the view that what was going on was all instigated, supported and controlled from the outside. Although it wasn't stated" in the documents "that it was to be the justification for beginning to send in troops, it's obvious that's what it was as it turned out," he charges.

Liechty says he has been hesitant to talk publicly about these episodes but decided to do so because "the point is that what is happening now in El Salvador looks so similar to what I saw of the agency role in preparing the groundwork for a big U.S. involvement" in Vietnam.

At the same time, however, he says he personally has "no doubts that the Soviets and Cubans have an interest in seeing the El Salvador guerrillas succeed."

Aside from having been involuntarily separated from the CIA, Liechty has also written a manuscript about his experiences which he hopes to get published and which has already gone through CIA censors for clearance. Much of his material has been censored, he says, but he asserts he has not decided to talk publicly out of bitterness toward his former employer.