A "National Dialogue Against Violence," organized by Guatemala's political parties, was canceled recently when many of the participants failed to show up-out of fear for their lives.

Even for the few who were not intimidated, the rising daily body count of leftist politicans and labor, student and peasant activists has made talk seem useless.

The current wave of assassinations, performed with Mafia-lke precision and apparent police blessing by anomymous right wing death squads, has effectively destroyed the first popular mass movement in Guatemala in the last quarter century.

On April 6, the body of union leader Manuel Lopez Balan was found with five others. Two wekks before, Manuel Colom Argueta, the highly popular former mayor of this city, was murdered by a team of at least 14 gunmen at midmorning on a crowded downtown street.

The level of organized terror frightens even the most violence-inured in this turbulent county. One local human rights agency estimated the number of politically motivated deaths and disappearances in the past year at more than 600.

The military-backed government of President Romeo Lucas Garcia has deplored the murders. The country's leading right-wing political party, the National Liberation Movement (MLN), accused in the past of sponsoring paramilitary death squads with names like The White Hand and Eye for an Eye, has denied responsibility.

There is confusion over whether the government, the MLN or both are responsible for the killings. But many Guatemalans-considering who the victims are and the cirumstances surrounding their deaths-have come to what they feel is the inescapable conclusion that one or both are involved.

The government and the MLN are staunch defenders of an economic and political status quo that has been threatened by a rising tide of labor and present militancy and the growing visibility of leftist political alternatives.

In response, at least six union leaders have been murdered in the past year. Others have left the country or gone underground. Activists within the Indian Community, which form more than half of Guatemala's population, report harsh interrogation and threats at the hands of local officials and civilian-dressed vigilantes. Rural villagers describe homes that are ransacked and relatives who disappears.

At a government-authorized demonstration in front of the presidential palace in October, student leader Oliverio Casteneda was assassinated by gunmen who escaped, ostensibly without a trace, while scores of security guards watched.

Two months before Colom Argueta's murder, social democratic leader and former foreign minister Alberto Fuentes Mohr was killed-again in broad day-light, on a crowded street in close promimity to police forces. The crime remains unsolved.

"For the first time," one peasant organizer said, "the popular movements from all sectors-the church, the peasants, labor, students-were beginning to band together to protest things. Before, if one group was attacked, it had to defend itself."

"But now, instead of attacking one group individually, it has come on all sides," the organizer said. "Anything that has to do with preparing local leadership has been presured."

Some analysts attribute the situation to the opening of previously unsettled territories in northern Guatemala and growing interest in the possibility of as yet untapped oil and mineral deposits clode to the Mexican border.

Portions of the north-central Transversal strip area and the largely virgin Peten in the far north were originally intended for road-building and resettlement of Indian and mixed race peasants who crowd into the central highlands and southern plains.

The roads are being built, but title to much of the increasingly valuable land has turned up in the hands of high-level military officers and plantation owners who already own three-quarters of Guatemala's cultivated territory.

Gen. Lucas Garcia, in charge of the strip devlopment program before his election as president, and his defense minister reportedly hold title to large tracts.

Conflicts over territory already have resulted in numerous deaths, including the massacre of at least 47 Indians by soldiers last May in the town of Panzos. The military and economic elite are anxious to avoid increased rural organization and demands for rights.

More immediately, the working class in Central America's most industralized nation has grown increasingly militant. Official response to demands and strikes such as last October's nationwide protest against increased bus fare has alternated between temporary acquiescence and harsh repression.

The nation's three public employe unions were shut down by the government for their support of the October strikes.

Many Guatemalans believe their government and the economic power elite have panicked over new activity from long dormant guerrillas in their own mountains and events in neighboring Nicaragua and El Salvador. Similarly powerful conservative minorities in those countries are threatened with all-out war by civilian groups and guerrillas.

Guatemala's civilian Vice President Francisco Villagran Kramer, brought into the government as part of an earlier compromise with liberals and now effectively isolated from government councils, summed up the thoughts of many in a recent interview.

"If one could enter the mind of a military president," Villagran said, "one could then explain many things."

As it is, in the words of one local journalist, confusion "is so elaborate that it neutralizes any ability to accuse and forms part of the strategy of terror."

At the time of his July 1 inauguration, Lucas Garcia gave a small amount of hope to some liberal sectors of Guatemalan society.

Pre-election jockeying to replace the former president, Gen. Kjell Laugerud, had left a peculiar lineup of candidates. The MLN, traditional spokesman for rightist civilians and military, split with Army moderates to nominate its own right-wing general.

On the left was another general, a liberal by Guatemalan standards. Lucas Garcia fell into the center by virtue of a marriage convenience between the moderate military hierarcy and left-leaning populists, including Colom Argueta, who felt he offered the best alternative in a bad situation.

In exchange for what amounted to the populists eschewing criticism rather than offering outright support, Lucas Garcia gave the vice presidency to Villagram, a prominent and respected liberal political scientist.

Gen. Lucas Garcia agreed that Guatemala's four official political parties would be expanded government registration of a number of groups that had been waiting with the required number of signatures for years. That registration, leftists like Colom Argueta believed, would open the doors for a real election in 1982.

In last year's vote count, which was bitterly disputed and called fraudulent by all sides, Lucas Garci emerged victorious.In the first months of the new administration, Villagran said, "we looked with good spirits at the future.

"We tried," he said, speaking for the leftists, "through a compromise with both capital [the private sector] and the Army, to see if we could break up the system and open the doors.

"We have failed."

Villagran described the change as a cumulative process, building with rightist pressure on the president as popular militancy increased and breaking loose about the time Lucas Garcia attended a secret meeting with beleaguered Nicaraguan President Anastasio Somoza at the end of last year.

The vice president no longer attends Cabinet meetings where he said he feels "the decisions are already taken" before he gets there. Villagran has spoken to the president only twice, by telephone, since early January. He has publicly threatened to resign and spends most of his days at home, surrounded by a large contingent of uniformed security guards, who were assigned by the government for his protection.

Others believe the escalation of rightist violence started with the beginning of Lucas Garcia's administration or even before. These observers, noting the similarity of the assassination attacks, the use of weapons and vehicles of the type used by the government, and the fact that there have been practically no arrests, believe the path leads directly to the government.

Recently, a new death squad appeared on the scene, calling itself the Secret Anticommunist Army. It issued clandestine mimeographed tracts and hit lists of union and present leaders similar to those of the MLN's old White Hand.

The MLN, which sent representatives to the "dialogue against violence," has hotly denied any responsibility for the terror. Some observers agree, noting that the right-wing party is ostensibly out of power and without direct control over the police and military.

Whoever is responsible, many liberal Guatemalans firmly believe the terror is under direct control of the country's land and money elite.

"It's very simple," the peasant organizer said. "They don't want a repetition of Nicaragua. They don't want civilian leadership in 1982. They want to protect their interests in the North, and they don't want Guatemala unionized." CAPTION: Picture, Guatemalan Indian youths return home from working fields in the highlands. By Karen DeYoung-The Washington Post; Map, no caption, By Dave Cook-The Washington Post