A Central Intelligence Agency document instructing Nicaraguan rebels in the techniques of political assassination and guerrilla warfare was denounced yesterday by the chairman of the House intelligence committee as "repugnant to a nation that condemns such acts by others."

Rep. Edward P. Boland (D-Mass.) said the 44-page document, "Psychological Operations in Guerrilla Warfare," is further proof of the dangers in the Reagan administration's active sponsorship of the contras fighting the leftist Sandinista government in Nicaragua.

In addition to rekindling questions about whether the administration's aim is to overthrow the Sandinista government, the document's detailed instructions on how to kill fleeing civilians or government officials seem certain to stir arguments about whether the CIA is violating rules prohibiting its personnel from engaging directly or indirectly in assassination.

The document's advocacy of political assassination, blackmail and mob violence also poses a major credibility problem for the administration because it has condemned those tactics as international terrorism when practiced by groups supported by such countries as Libya, Iran and Syria.

Boland charged that the House Permanent Select Committee on Intelligence knew nothing about the document, which the CIA produced and gave to the contras last year, until its existence was revealed by the Associated Press this week. He likened the situation to the CIA's failure earlier this year to tell the committee about its complicity in the mining of Nicaraguan harbors.

The controversy generated by the mining was a key factor in Congress' decision to cut off U.S. funding for the contras, at least until March.

"Like the mining, the manual is a disaster for American foreign policy," Boland said. "I am appalled by the image of the United States that the manual portrays. Something such as this manual points to the wisdom of congressional action to cut off funding for the secret war. Unfortunately the cutoff comes too late to repair the damage in this instance."

Boland's sharp criticism was echoed by other members of Congress. Rep. Michael D. Barnes (D-Md.), chairman of the House Western Hemisphere affairs subcommittee, called the manual an "outrage and almost certainly a violation of the rules governing the CIA." Sen. Edward M. Kennedy (D-Mass.) said "aiding and abetting a strategy of political assassination is unacceptable in American foreign policy . . . . " Sen. Daniel Patrick Moynihan (D-N.Y.), vice chairman of the Senate Intelligence Committee, said he will ask the CIA for a report on the matter by Friday.

The CIA has refused to comment publicly on the document, which was written in Spanish and has been translated into English by the Congressional Research Service. But U.S. officials have confirmed privately that it is authentic.

The manual amounts to a course on how to organize a guerrilla movement and lead it to power by winning popular support and using violence.

In discussing how to gain control over towns, it says that if "it becomes necessary" to shoot a citizen "trying to leave the town," the guerrillas should justify their action by claiming that the victim was "an enemy of the people" who would have "alerted the enemy" and permitted the Sandinistas to "carry out acts of reprisals, such as rapes, pillage, destruction, captures, etc."

At another point, the document states: "It is possible to neutralize carefully selected and planned targets, such as court judges, police and state security officials, etc."

The manual stresses that "it is absolutely necessary to gather together the population affected, so that they will be present and take part in the act," with the guerrillas explaining "why it was necessary for the good of the people" to "neutralize the target official."

Boland said "this conscious targeting of individuals" to be eliminated "embraces the communist revolutionary tactics that the United States is pledged to defeat throughout the world." He contended that such tactics prove that the administration's aim in the covert war is not merely to halt Sandinista aid to leftist guerrillas in El Salvador but "to overthrow the Sandinista government."

Many of the tactics have been described in published works by scholars and journalists who have analyzed guerrilla campaigns in Cuba, Malaysia, the Philippines and several African countries. Specialists also have noted that the techniques are similar to those used by the Vietcong.

But while much of the material is available in other texts, there are certain to be questions about the legality of the CIA covertly advising the contras on how to pursue tactics that are prohibited under agency rules.

The rules were promulgated in 1976 by President Gerald R. Ford after lengthy controversy and investigation of CIA abuses of power. They specifically forbid anyone "employed by or acting on behalf of the U.S. government to engage in, or conspire to engage in, assassination" or to "encourage directly or indirectly" other persons to engage in prohibited activities.

The tactics described in the document also appear at odds with the administration's condemnation of terrorism. In a June 24 speech, Secretary of State George P. Shultz said: "It is not hard to tell, as we look around the world, who are the terrorists and who are the freedom fighters. The resistance fighters in Afghanistan do not destroy villages or kill the helpless. The contras in Nicaragua do not blow up school buses or hold mass executions of civilians."

Asked yesterday whether Shultz's remarks were still a statement of administration policy, State Department spokesman Alan Romberg said, "Certainly." But when asked how Shultz's statement squared with tactics advocated in the CIA document, Romberg replied that government policy precludes discussing intelligence matters in public.