The United States Central Intelligence Agency has denied any involvement in death-squad activity in El Salvador, but investigation of such alleged involvement is under way at several levels.
Two senators said that through a briefing to members of the Senate Select Committee on Intelligence last Thursday, the CIA made a strong denial that it had any links with Salvadorean death squads, or assassination teams.
But congressional sources also said that CIA abuses were still possible and that the matter will be pursued through Senate Intelligence Committee hearings, through the CIA's own internal auditing procedures, and through additional governmental investigation. A Senate staff-level working group set up some weeks ago is focusing on the full range of death-squad activities in El Salvador.
The Christian Science Monitor reported May 8 that the CIA and US military advisers had helped organize, finance, train, and advise special Salvadorean Army and intelligence units that, although presumably set up for counterintelligence purposes, subsequently have engaged in death-squad activities.
The Monitor report said that these units, in the course of their intelligence activities, frequently torture and sometimes kill Salvadorean citizens - apparently with the knowledge of their US mentors.
On the day that the article appeared, the State Department issued a statement saying, among other things, that the US was interested in eradicating such violence and not in condoning it. The State Department referred reporters to the CIA for further comment.
In its statement on the subject, the CIA described as ''outrageous'' allegations of CIA linkage to death-squad activities, including training in torture techniques.
''The CIA does not condone, participate in or promote, by instruction or by any other means, murder or the use of torture,'' the CIA statement said. ''Moreover, the US intelligence services are prohibited from engaging in assassination by presidential executive order.''
In keeping with their usual reticence on matters involving intelligence, a number of senators and congressmen declined to comment on the report linking the CIA with death-squad activities or on the CIA's subsequent denial. But all of those who did comment, both in the Senate and House, made the point that they were continuing to ask questions about the allegations and expected further, more-detailed CIA responses.
''I'm having the story investigated,'' said Rep. Lee H. Hamilton, the Democrat from Indiana who is expected to succeed Democratic Rep. Edward P. Boland of Massachusetts as chairman of the House Select Committee on Intelligence.
Two Republican members of the Senate Committee, William S. Cohen of Maine and David F. Durenberger of Minnesota, agreed to describe the meeting last Thursday at which John Stein, the CIA's deputy director for operations, answered senators' questions concerning the Monitor report.
''The CIA made a point-by-point rebuttal,'' said Senator Cohen. ''They did appear to have a credible case. . . . They pointed to some fairly significant factual discrepancies (in the Monitor report).''
Senator Durenberger said that in the course of a more than two-hour-long meeting, the committee members gave Mr. Stein a sharp ''grilling,'' in part because they felt that the CIA had not been fully forthcoming with them in the past on the subject of the intelligence agency's involvement in the mining of Nicaraguan harbors.
''It was very intensive,'' said Durenberger. ''A lot of people were shell-shocked before because they didn't ask the right questions about the mining.''
The Minnesota senator said the consensus of the committee members - there was a majority of the committee's eight Republicans and seven Democrats present at last Thursday's meeting with Stein - was that the CIA official had made a ''pretty substantive denial.''
According to Durenberger, Stein argued that the CIA trains its people not to mistreat prisoners.
Durenberger said Stein specifically denied that a US Embassy official of Cuban-American background who was mentioned in the Monitor story worked for the CIA.
A State Department official later said the Cuban-American in question had, at a number of overseas posts, done work that would have been of little use to the CIA.
''We came away satisfied that the specifics of the story have no basis in fact,'' said Durenberger.
But Durenberger said it was possible that abuses had occurred in El Salvador that were not known to top CIA officials in Washington. And, like Cohen, he stressed that the Senate committee was still looking into the subject. He said CIA officials did not seem to be reticent about the possibility at some point of showing senators or their staff files that might relate to the subject.
But some congressional sources who were not present at the meeting came away with the impression that Stein did not deny that field-level CIA officers might have some knowledge of death-squad activities carried out by Salvadorean intelligence agencies with which they worked. Nor did Stein apparently deny the existence of the Salvadorean National Intelligence Agency (ANI) or CIA links with that agency.
The question of possible CIA links with elements of the Salvadorean security forces engaged in death-squad activities arose in March of this year, when the New York Times reported that Nicolas Carranza, the head of El Salvador's Treasury Police, had been a paid informant for the CIA since the late 1970s. The Times quoted American officials as saying that Colonel Carranza had received more than $90,000 a year from the CIA for the last five or six years. The Treasury Police are considered by some observers both here and in El Salvador to be the most brutal of the Salvadorean security forces.
On April 3 of this year, Democratic Sen. Edward M. Kennedy of Massachusetts asked for an examination of the alleged CIA-Carranza link and of the nature of death-squad activities by the Senate Select Committee on Intelligence. The chairman of that committee, Sen. Barry Goldwater, told Senator Kennedy that hearings would be held on the subject before the end of May. As a result of Kennedy's request, the Senate Intelligence Committee also established a working group consisting of 12 of the committee's professional staff members to look at the full-range of death-squad activities.
Democratic Sen. Daniel Patrick Moynihan, vice-chairman of the Senate committee, said in early April that the committee had not been indifferent to the death-squad question but that nothing it had learned up to that point would in any way implicate the CIA in such activities. An aide said the senator would not comment on the Monitor's May 8 article.
In the House of Representatives, on March 22, Democratic Rep. James M. Shannon of Massachusetts introduced a resolution calling on the executive branch to furnish the House Permanent Select Committee on Intelligence with all CIA documents relating to possible agency payments made to Carranza or to Roberto d'Aubuisson, the Salvadorean presidential candidate who has been frequently accused of having links with some of the death squads. A former Salvadorean military official who was promised $50,000 by a group of critics of Reagan administration policies if he would speak out has made repeated assertions that Carranza worked for the CIA and was involved with death squads. Carranza and d'Aubuisson have denied such allegations.
On April 25, the House Intelligence Committee issued a three-page report saying that in a limited but ''exhaustive'' review of intelligence documents and records that relate to or make mention of either Carranza or d'Aubuisson, the committee found no evidence of CIA complicity in death-squad activities. But it said that a full review would be needed to lay to rest charges alleging relationships with the death squads.
Mr. Shannon told the Monitor he did not think the House Intelligence Committee's report was the final word. He said the committee had referred the matter back to the CIA's inspector general.
''There is a real question in my mind whether the CIA has been forthright on the issue,'' said Shannon.
The Massachusetts congressman said he doubted whether Jose Napoleon Duarte, El Salvador's president-elect, had the strength to control the Salvadorean military and security forces and curb the death squads.