In the first of what may be several similar cases the U.S. Immigration and Naturalization Service has initiated procceedings that could lead to the deportation of a former high South Vietnamese official now living in the United States.

Apparently bowing to congressional and public pressures, the INS has moved to rescind the permanent resident status of former South Vietnamese brigadier general and chief of police Nguyen Ngoc Loan, who was photographed killing a bound prisoner on a Saigon street during the Tey offensive of 1968.

The picture of Loan summarily executing a suspected Vietcong with a snub-nosed pistol drew wide attention in American during that crucial year of the war. Since the end of the conflict, Loan has lived quietly in Washington's Virginia suburbs, trying to build a life as the proprietor of a small restaurant.

The INS now contents in a legal proceeding against Loan that he should have been tried in Vietnam for the execution, a war crime, and that his permanent resident status should be rescinded on the grounds of "moral turpitude." Loan's lawyer has said that he will argue the Vietnamese general was acting legally, under the edicts of martial law, at the time of the killing.

Loan's presence in the United States has been frequently cited in the press and on Capitol Hill as the most conspicuous - though far from the only - example of South Vietnamese officials who have been allowed to remain in the U.S. despite their alleged involvement with crimes ranging from tortue to drug trafficking under the Saigon regime.

The INS has been under fire from various congressmen since 1975 for its apparent inability, or unwillingous, to investigate and act on such allegation. The congressmen contend that these South Vietnamese officials, if guilty of the crimes, had no right under the Vietnamese refugee program to enter the U.S. or to remain in the country.

During the summer of 1975 Bep-Elizabeth Holtman (D-X.Y.) forwarded to the INS a list of such Vietnamese refugees published in New Times Magazine. In a reply to Holtzman's inquiry, the INS reported that a former general on the list, who was reportedly "the biggest pusher" of heroin in Vietnam, had "proceeded to Canada." Another, who had allegadly profited from the 1963 coup of South Vietnamese president Ngo Dinh Diem, had applied for "resettlement in a third country," the INS said.

The INS letter to Holtxman reported that several men named in the New Times article, including former South Vietnamese vice president nguyen Cao Ky, had been "security cleared under investigation, and nine, including Loan, had been located as of August 1975.

After Loan's residence in Fairfax County was reported in The Washington Post and other papers in 1976, however, public and congressional pressures for action were renewed.

Holtxman, who had introduced a reequprement that refugees swear they had not been involved in penaccution in Vietnam, questioned INS Commissioner Leonel J. Castillo about he matter during House immagration subcoimmittee hearings in May 1977. She was assured by Castillo that specific cases would be reexamined.

At subsequent hearings, Rep. Harold Sawyer (R-Mich.) questioned immagration officials specifically about Loan. Sawyer said yesterday he was told that Loan had not committed a crime under South Vietnamese law. But Sawyer said that he also then requested the Library of Congress to research the issue. The results of the library's report, which concluded that summary execution of such nature were illegal under Vietnamese law at the time, were forwarded to INS last spring.

Last summer, the INS notified Loan permanent resident status. A hearing on that issue has not yet been scheduled, but if the INS wins its case, a spokesman said yesterday, it may then move to deport Loan.

If it is found that he cannot be sent back to Vietnam for fear of political "persecution" there, and no other country will accept him, however, Loan may be allowed to continue living in the United States as "a stateless person," the INS spokesman said.

An INS spokesman said lst night that there "is a likelihood that there could be several more "similar cases like the Loan case." Both Holtzman and Sawyer said yesterday that they would continue the pressure to find, investigate and if neccessary deport offenders.