MEXICO CITY, JUNE 12 -- In its first comprehensive report on Mexico, the U.S.-based human-rights group Americas Watch charged today that disappearances, killings, torture and other violent human-rights abuses by security forces have become "institutionalized" in this country and that the government lacks the "political will" to end them.

The highly critical 115-page report, entitled "Human Rights in Mexico: A Policy of Impunity," asserted that the Federal Judicial Police, especially its elite anti-narcotics unit, were responsible for some of the most serious cases of torture and murder, as well as "extortion and robbery."

While the Mexican government has promoted human rights internationally, it has responded to charges of rights violations at home with "public relations ploys rather than real attempts to curb abuses," a summary of the report said. The full report noted that Mexican police have been arrested on torture or slaying charges in "a handful of highly publicized cases" but that the number of such arrests "is minuscule compared with the extent to which such practices occur."

According to Americas Watch, "This pattern of excessive violence and abuse can only mean that either the Mexican government has adopted a policy of tolerating such behavior, or it has lost control over its police security and prosecutorial agencies."

Although the human-rights group congratulated the government of President Carlos Salinas de Gortari on its creation of a new National Commission on Human Rights, it offered a gloomy forecast of future violations.

"Recent events portend that rather than moving toward improvements in human-rights conditions, Mexico may be heading for a period of increased violent abuses and suppression of dissent," it said, citing the government's military response to recent election-fraud protests.

Listing "election-related violence" as a major area of rights abuses, Americas Watch called on the government to ensure that "federal, state and local elections are free and fair so that they do not give rise to allegations of fraud."

The government had no immediate reaction to the strongly worded report, which was issued as Salinas concluded a three-day visit to Washington.

Last week, a day after Salinas created the new human-rights commission, his government emphatically rejected a report by the Inter-American Commission on Human Rights that documented election fraud by the ruling Institutional Revolutionary Party (PRI) in state elections in Chihuahua and Durango in 1985 and 1986. The commission, an arm of the 32-member Organization of American States, said that the election results for state legislators and governor in Chihuahua and for mayors in Durango were "not authentic because they did not represent the popular will."

The conservative opposition National Action Party (PAN), which argued that it was cheated of victory in those elections, demanded that the government respect the OAS report and called for the resignation of the "impostor" governor of Chihuahua, Fernando Baez, who took office in 1986.

In an OAS meeting in Paraguay last week, the Mexican delegation called the report "clear interference" in Mexico's internal affairs and refused to recognize "the competence of the Inter-American Commission on Human Rights to pronounce itself on these cases." The delegation asserted that Mexico enjoys "a democratic system in which all the political parties participate."

Opposition parties charge, however, that the PRI, which has ruled Mexico for 61 years, continues to steal elections. Since the party was founded in 1929, it has conceded only one loss of a state governorship -- in Baja California Norte last year -- and has held the presidency without interruption.

In its report today, Americas Watch noted that some powerful PRI officials have expressed concern about a resurgence of leftist guerrilla groups in Mexico that could threaten national security. However, it said it found "no evidence" of such a threat.

Among the current abuses cited by Americas Watch is "physical and psychological torture," which it said is "used routinely in law enforcement to this day" despite 1986 legislation specifically forbidding it. That law came in response to a public outcry when tortured bodies were found in the ruins of the attorney general's headquarters after Mexico City's September 1985 earthquake.

"Torture is endemic in Mexico," the report said. "It occurs in all parts of the country and is practiced by most if not all branches of the federal and state police, as well as by the armed forces." It said methods range from beatings and near asphyxiation to electric shocks and spraying carbonated water laced with chili peppers up the victim's nose.

The report charged that federal anti-narcotics police "are accountable for a large number of cases of murder, torture and abuse of process in Mexico today" and are "widely reputed to be corrupted by involvement in or covering up of drug trafficking." However, the document provided no evidence of drug-related corruption in the unit, which has seized more cocaine in the first 18 months of the Salinas government than was confiscated during the six years of the previous administration.