An internal report to the State Department from the U.S. Embassy in Guatemala charges that "conscientious human rights groups and church organizations" lobbying against military aid to that Central American country are the victims of a "concerted disinformation campaign" by "groups supporting the left-wing insurgency" there.

The document is described as an analysis of reports by Amnesty International, the church-funded Washington Office on Latin America (WOLA) and two other groups that have charged the Guatemalan armed forces with carrying out a series of massacres of civilians in their war with leftist insurgents.

The Embassy report was obtained from sources not linked to any of the groups or to the State Department, and a State Department official said the report never was meant to be made public.

Representatives of the groups, however, said the State Department report was a distortion of their research on the Guatemalan human rights situation. They said the report may be an effort to discredit them during the congressional debate on the Reagan administration's announced plan to sell $3 million to $5 million in helicopter spare parts and communications equipment to the Guatemalan government of Gen. Efrain Rios Montt.

Military sales and assistance to Guatemala have been suspended since 1977 after reports of widespread human rights violations there. Since Rios Montt took power in a military coup in March, the Reagan administration has praised the new government for improving the human rights situation and generally backed the government in blaming the guerrillas for the massacres.

The embassy report says, "Although the embassy believes it likely that the Guatemalan Army has indeed committed some atrocities, the assertion that they committed all the massacres attributed to them is not credible, especially since analysis indicates the guerrillas are responsible in many cases."

The embassy report cites Guatemalan "press, Army and police reports" to back its claim that "terrorist groups" have committed human rights abuses against civilians not reported by the human rights groups. According to state of siege restrictions in force since July 1, all Guatemalan press reports on military activity must be taken from official military communiques.

The embassy's report says human rights groups "are being utilized" by guerrilla supporters, who "intend to win the war against the GOG Goverment of Guatemala by making the U.S. Congress the battlefield." To back that charge, the embassy report said the human rights reports cite many of the same alleged atrocities and "are drawing on many of the same sources . . . most of which are well-known extreme left-wing advocacy groups in Central America and in the U.S."

A State Department official said, however, "We are not trying to impugn" the human rights groups' "integrity or motives . . . .We're trying to come up with objective information." He added that the department has "not given copies to Congress or the public."

Patricia Rengel of Amnesty International's office in Washington said the embassy's report was "a very serious and flawed depiction" of Amnesty's methods and reports. "We don't have a political agenda," she stressed. "It's an attempt to discredit Amnesty's information."

Aryeh Neier, vice chairman of Americas Watch, another human rights monitoring group that sent a mission to Guatemala in October, said: "The State Department ought to be ashamed of itself. Amnesty International is infinitely more careful in the way it documents its information than the State Department."

Reggie Norton of WOLA said he had provided a list of incidents to the State Department at its request--apparently the list the embassy report refers to as the "WOLA/NISGUA report--but had made it clear to the State Department that the list had not been checked or verified and was not an official WOLA document. "It was not a report. It was just a list, and we never made it public," Norton said.

He said the list also contained reports received by a pro-insurgent group, the Network in Solidarity with the Guatemalan People (NISGUA), which is not related institutionally to WOLA. The embassy report also criticized the Guatemalan Human Rights Commission.